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Old 07-16-2013, 12:20 PM   #1
WRXinpa
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Default Resonator Install

I am going to install a 12-inch or so resonator on the mid-pipe of my SPT quad tip hatch exhaust. My question is, will a resonator with advertised inlet and outlet dimensions of 2.5 inches SLIDE OVER the SPT's 2.5 inch midpipe (after I cut out a section)?

Also, do band clamps provide a tight seal for this application? Thanks
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Old 07-16-2013, 04:41 PM   #2
Malin726
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I am not a mechanic nor do I play one on TV. So take my advice as you will.
I would not trust an "advertised" inlet or outlet unless it was an SPT resonator.
Get the proper dimensions before you take a knife to it. And my .02 is to not use band clamps and get a proper clamp from your local parts store and tac weld if you can't fully weld it.
Then of course is the best end result. Take it to a shop.
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Old 07-16-2013, 04:55 PM   #3
sc00by4life
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if something has an ID of 2.5", why the hell would you think it'd fit OVER a pipe of the same dimensions?

I wouldn't use v-bands or clamps....it needs to be welded in.

and why do you want to put an extra resonator on your SPT in the first place?
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Old 07-16-2013, 05:01 PM   #4
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Ok why would you want to slide a resinator over the pipe and not just either buy a resonator with a flange on each end so you can use a gasket on each end and bolt each up up to the exhust and mid pipe so you get a nice clean look and a tight seal? If you couldnt do this why wouldnt you weld each end together to make a nice tight seal so you know you dont have a leak anywhere? By sliding 1 pipe over the other your not gonna get a good seal and could end up with a leak plus its not gonna look great. I know its under the car and nobody will see it but this isnt the correct way to do things its kind of a rigged up cheap way to do it. The last thing I am gonna say/ ask is if you have a resinator that 2.5 in on each side and an exhust thats 2.5 in how do you plan on slide 1 over the other if they are the same size? 1 needs to be smaller then the other to be able to slilde 1 over the other. Or am I missing something here?
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Old 07-16-2013, 05:07 PM   #5
sc00by4life
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Quote:
Originally Posted by Masta Splint View Post
Ok why would you want to slide a resinator over the pipe and not just either buy a resonator with a flange on each end so you can use a gasket on each end and bolt each up up to the exhust and mid pipe so you get a nice clean look and a tight seal? If you couldnt do this why wouldnt you weld each end together to make a nice tight seal so you know you dont have a leak anywhere? By sliding 1 pipe over the other your not gonna get a good seal and could end up with a leak plus its not gonna look great. I know its under the car and nobody will see it but this isnt the correct way to do things its kind of a rigged up cheap way to do it. The last thing I am gonna say/ ask is if you have a resinator that 2.5 in on each side and an exhust thats 2.5 in how do you plan on slide 1 over the other if they are the same size? 1 needs to be smaller then the other to be able to slilde 1 over the other. Or am I missing something here?
first things first. lets break your post down. Yes. You are missing a lot.

Quote:
Originally Posted by Masta Splint View Post
Ok why would you want to slide a resinator over the pipe and not just either buy a resonator with a flange on each end so you can use a gasket on each end and bolt each up up to the exhust and mid pipe so you get a nice clean look and a tight seal?
This would require removing a section of the midpipe, fabbing up (or buying) flanges, having them welded on, so you could simply "bolt in" the resonator. That's a ton of work for something that would have no other use and would render the catback useless unless you found the one other person in the universe that wants an SPT exhaust with an extra resonator.

Quote:
Originally Posted by Masta Splint View Post
If you couldnt do this why wouldnt you weld each end together to make a nice tight seal so you know you dont have a leak anywhere? By sliding 1 pipe over the other your not gonna get a good seal and could end up with a leak plus its not gonna look great.?
sliding a resonator OVER the pipe would not accomplish anything. They are designed to have exhaust run THROUGH them....not through a separate pipe down the middle. Its a tuned cavity designed to reduce sound.
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Old 07-16-2013, 09:15 PM   #6
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Quote:
Originally Posted by sc00by4life View Post
if something has an ID of 2.5", why the hell would you think it'd fit OVER a pipe of the same dimensions?

I wouldn't use v-bands or clamps....it needs to be welded in.

and why do you want to put an extra resonator on your SPT in the first place?
Why would I put a (not an extra) resonator on the SPT? Because I want to reduce the drone. In case you haven't experienced the SPT with a hatch it can drone, and drone a lot. Anyway, I'm thinking of just cutting out the stock exhaust resonator and having that welded into the SPT at the same point as OEM.
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Old 07-16-2013, 09:45 PM   #7
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Quote:
Originally Posted by WRXinpa View Post
Why would I put a (not an extra) resonator on the SPT? Because I want to reduce the drone. In case you haven't experienced the SPT with a hatch it can drone, and drone a lot. Anyway, I'm thinking of just cutting out the stock exhaust resonator and having that welded into the SPT at the same point as OEM.
Isn't 12" a small resonator? I had 18" on my Spec V and wished I went 22". Not sure what kind of room we have under there though.

Do you think the resonator will affect only the drone and not the rest of the range? I feel like adding another resonator (or replacing the stock one) will make the car sound closer to a stock/non-SPT WRX.
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Old 07-16-2013, 10:45 PM   #8
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Quote:
Originally Posted by sc00by4life View Post
and why do you want to put an extra resonator on your SPT in the first place?
I might be wrong, but I don't think the SPT for the 2011+ WRX hatch has a resonator in the midpipe.
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Old 07-16-2013, 11:59 PM   #9
nonamekevin
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Yea I haven't seen the SPT for the 11+ Hatches with a resonator.

-Kevin
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Old 07-17-2013, 06:31 AM   #10
tomacGTi
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Why not bolt the stock resonator onto the SPT axleback and see if that's what you're looking for first? They should mate up fine. IIRC stock should be the same size tubing.

I would then take the whole thing to a good fab shop and weld in the biggest resonator you can fit in there on. That or find a quieter exhaust and sell off your unmodified SPT to fund it.

Here's an example:

I just went through a similar situation with a different car: had a Borla rear muffler, the second resonator over the axle (part of the aftermarket exhaust system) and a non-resonated midpipe. LOUD. Like hear you from three blocks away loud. A bit of interior drone as well and had a raspy note to it. Added a midpipe resonator (it was optional for this exhaust) and it toned the exhaust down drastically. Much smoother sound, interior drone eliminated and made it more acceptable to drive around without sounding like you were racing everything. Made the car more "mature" you would say.

You already have all the parts, why buy or modify if you don't have to?

My .02$

-Randy

Last edited by tomacGTi; 07-17-2013 at 06:40 AM.
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Old 07-17-2013, 06:56 AM   #11
Jayp5150
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Quote:
Originally Posted by tomacGTi View Post
Why not bolt the stock resonator onto the SPT axleback and see if that's what you're looking for first? They should mate up fine. IIRC stock should be the same size tubing.
Stock and SPT midpipes have a different axleback flange location. They aren't interchangeable.

I keep reading all these "my SPT is loud and drones" posts and I feel like mine is defective haha.

I believe someone here did this recently. You could dig up his post and see what his results were.

Edit:I found it. http://forums.nasioc.com/forums/show....php?t=2363002

Last edited by Jayp5150; 07-17-2013 at 07:10 AM.
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Old 07-17-2013, 07:35 AM   #12
tomacGTi
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There I go ASSuming again. Sorry about that.

Looks like there's your answer. I see a sparkle wrench and a resonator in someone's immediate future.

And for reference sake: a drop of 6 dBs is huge. It will be extremely noticeable.
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Old 07-17-2013, 09:32 AM   #13
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Quote:
Originally Posted by tomacGTi View Post
There I go ASSuming again. Sorry about that.

Looks like there's your answer. I see a sparkle wrench and a resonator in someone's immediate future.

And for reference sake: a drop of 6 dBs is huge. It will be extremely noticeable.
You adding "Sparkle Wrench" to my vocab makes up for any assumption! lol
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Old 07-17-2013, 10:27 AM   #14
WRXinpa
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Quote:
Originally Posted by tomacGTi View Post
There I go ASSuming again. Sorry about that.

Looks like there's your answer. I see a sparkle wrench and a resonator in someone's immediate future.

And for reference sake: a drop of 6 dBs is huge. It will be extremely noticeable.
Yeah 6 dB is huge (log scale), not looking to go for that much reduction. In fact id be fine with no noise reduction, just drone ELIMINATION!

I had seen that post before. Would have been nice if the OP gave the model #.
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Old 07-17-2013, 10:38 AM   #15
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I had used a 12" long, 3" Dynomax race bullet on my old car (98 GTP). I had been running catless, and was tired of the rasp and resonance.

That did mellow it down a bit, but definitely didn't make it much quieter.

I later added a 18" glasspack in the midpipe, and had the similar results. That obviously did quiet it down a tad more than the race bullet, but it still wasn't a drastic difference.

If you do go with a glasspack type resonator, just remember it will be much quieter on initial install. Should break in some after a couple weeks.

I didn't measure db on either one, though.

You could always do the redneck muffler test... plug one side of the tips and hold up the new muffler to the other one lol. Or make lion noises through it. Same results.
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Old 07-17-2013, 06:32 PM   #16
WRXinpa
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Quote:
Originally Posted by Jayp5150 View Post
You could always do the redneck muffler test... plug one side of the tips and hold up the new muffler to the other one lol. Or make lion noises through it. Same results.
Finally, the scientific answer I was looking for...Its my impression that glass packs don't mellow just the sound much at all, just add some rasp.

I'm going to get under the car shortly and see what size resonator I can fit on the SPT midpipe, then I'll order it, then I'll have it welded on, then I'll post how it did nothing. Thanks everyone for your smartass input.
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Old 07-17-2013, 07:09 PM   #17
Jayp5150
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Quote:
Originally Posted by WRXinpa View Post

Finally, the scientific answer I was looking for...Its my impression that glass packs don't mellow just the sound much at all, just add some rasp.

I'm going to get under the car shortly and see what size resonator I can fit on the SPT midpipe, then I'll order it, then I'll have it welded on, then I'll post how it did nothing. Thanks everyone for your smartass input.
I was actually trying to help lol. I know they are markedly different cars, but that's the only add-a-muffler experience I had. On the GTP the glasspack did tone it down, but it was also blowing through a pair of single chamber welded mufflers (Flowmaster style) after it, so there was a lot of rasp and high end to start with. The SPT doesn't have that.

You have a lot of room under there. Please post back, I'm curious, just not for my car.

Good luck.
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