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Old 03-30-2004, 11:20 PM   #1
mycarsux
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Have a Nice Day? why did my car get slower

i just put on borla headers and now have a custom midpiipe with apexi n1 muffler. it doesnt seem to pull hard anymore. it seems like my car got slower. my used to start pulling hard after 3500 rpm. now it doesnt pull hard anymore. or was it that my car just didnt have any power before 3500 rpm and then all of it came after it (on my previous set up. stock headers, stromung muffler.) im really confused. i thought headers was suppose to make it better. i think my fuel mileage got better tho.
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Old 03-31-2004, 12:47 AM   #2
TexRex8
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Maybe less b/c of less torque at lower rpms...i dunno. I put my uppipe, catback, and boost controller on and it doesnt feel as jumpy right from the start, but whenever i bring those rpm's up, all hell breaks loose.
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Old 03-31-2004, 01:13 AM   #3
AustinSTi
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reset the ecu ??
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Old 03-31-2004, 01:15 AM   #4
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if you went with 3" piping, you'll lose low end torque in an rs...i think even 2.5" will drop it a bit...best to stick with 2.25" for NA
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Old 03-31-2004, 07:28 AM   #5
Imprezive2002
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yea man and what is the size of pipeing on the exhaust out, mine use to be 3 inch but that messed me all up so i changed to a hks 2.25 muffler out. Now it runs like its suppose to, i also have borla headers now it just whips it out haha `Nick
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Old 03-31-2004, 10:08 AM   #6
Pat L.I.
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MyCarSux - if you just put the headers on recently reset the ECU and give them some time to break in. I noticed this when i first installed my borla headers, they felt slower, i eventually got the power back.

you may also "feel" slower because the power delivery is smoother rather than a surge at 3,500 like before.
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Old 03-31-2004, 02:18 PM   #7
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What piping did you get after the cat? Mandrel bends? Badly-formed crush bends?

In any case, if the piping is correctly sized for your car and minimal/smooth bends, it may be that your car is more powerful, but not as peaky as it was before. As Pat is saying above, if the power curve is flattened (from additional torque) at lower rpm, there won't be the "kick" at 3500-4000. You'll be at the same power output, or higher, but not as peaky.

Ride the wave - Torque!
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Old 03-31-2004, 06:35 PM   #8
poison
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I think one of your stickers must've fallen off
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Old 03-31-2004, 07:53 PM   #9
mycarsux
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well i didnt put my borla sticker on so maybe dats why... i went wi/ 2.5 inch piping. i knew i should of gone to 2.25 but the apex resonator i had was 2.5. o well. the bends are mandrel...but not much bending was needed. if u look under my car, the mippipe runs parrellel with the driveshaft, so its pretty straight. does reseting the ecu help? i thought it only worked for intake or pulley kinda mods. if i dont reset it, will my ecu "learn" or something...i dunno im totally clueless on all the electrical/computer stuff.
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Old 03-31-2004, 08:31 PM   #10
DisturbedKayos
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mycarsux - i had the same problem your describing as well. i have custom made 2.5 inch headers, high flow cat, and 2.5 mandrel cat back into a naxos muffler. give it a week or so and everything will work out. and trust me, after that week has gone by, you will be a happy camper.
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Old 03-31-2004, 09:59 PM   #11
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Yeah, resetting the ECU probably will help. The ECU needs to "learn" the new parts, especially when it has to do with the air velocity and breathing characteristics. And freeing up the whole exhaust is definitely going to change that. And, no, you don't have to reset it, it will lear eventually, it's just that resetting it forces the issue, and is usually a faster method.
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Old 04-01-2004, 01:51 AM   #12
mycarsux
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oooh...tight. cant wait. by the way, how many miles is it to break in a muffler?
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Old 06-02-2004, 03:11 AM   #13
TNT
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Quick Bump.

I just installed a new midpipe and STI Exhaust.
Will I need to reset the ECU?
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Old 06-02-2004, 09:35 AM   #14
Pat L.I.
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sure go ahead it wont hurt! it will take a few driving cycles to learn, but you can speed up the process if you reset the ecu. Only takes a few minutes anyway.
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Old 06-02-2004, 12:29 PM   #15
Kevin Thomas
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Question Sooo

Those of you (if any) that have a 3" exhaust, does the ECU learn and bump up the torque as well? I know that the air velocity may be slowed down some. How about going with a 3" exhaust that narrows down to a 2.25 or 2.5" muffler?
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Old 06-04-2004, 11:16 AM   #16
Section 8
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The 3" pipe will not aid torque production no matter what the computer does.

A smaller muffler section won't help because the exhaust will slow down through the wide portion, but you will be using exhaust energy to speed up the gas through the narrowed muffler section.

The only place where a norrowing after a wide area helps is the collector of a header. After that for maximum effeciency (minimum loss) you need to have the same cross sectional area to the tail pipe, and choose you sound suppression wisely.

cheeRS,

Greg
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