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Old 04-17-2008, 07:04 PM   #1
WrxRick
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Default Will I lose power with no muffler?

I am building my STi as a weekend car/road course car. I want a 3" catless downpipe followed by a 3" straight pipe catback exhaust exiting right past the back bumper without a single muffler or resonator.

I have run open downpipe before and I do not like how laggy the car feels (the bottom end power is just not there). I just want to make sure my low end power will not suffer due to not having a single muffler.

Will my car react quite similarly, in terms of spool and power, as if I were to use any aftermarket 3" catback? Will I still suffer from lack of low end response? Does an aftermarket muffler really add to back pressure?

I don't believe this topic has been discussed.
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Old 04-17-2008, 08:23 PM   #2
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Yes, it's been asked before. Read the Exhaust FAQ...it states that zero back pressure is best. EVERY muffler adds backpressure. So......
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Old 04-17-2008, 08:25 PM   #3
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No just your hearing!
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Old 04-17-2008, 08:52 PM   #4
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i ran an electronic exhaust cutout for a couple months. (and will be again soon). catless downpipe.

so basically my exhaust was 3 inch about 2.5 feet long with no cats...no backpressure.

car seemed to go a lil faster.
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Old 04-17-2008, 09:20 PM   #5
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But the low end power....will I still have any?
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Old 04-17-2008, 10:17 PM   #6
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i was worried about the same thing before. dont worry
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Old 04-18-2008, 12:32 AM   #7
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You lose all teh j00r backpreshurz! zomg!
As it was stated, 0 backpressure /an unrestricted exhausted is the best exhaust.
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Old 04-18-2008, 12:45 AM   #8
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I thought the torque loss due to no backpressure was a myth because the turbo creates its own due to being in the exhaust path. Post turbo least restriction is best as previously stated
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Old 04-18-2008, 02:17 AM   #9
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Thanks. I put the exhaust on the car in 2 weeks.
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Old 04-18-2008, 02:32 AM   #10
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the only thing i can tell you with your setup...

you will get sick of a straight pipe. look into quicktimeperformance.com

seriously. straight pipes are cool, but after a while it just gets to be tooo much. i had a shop put my e-cutout on my catless downpipe, and that was mated to the stock catback. loud as balls when i wanted. silent when i needed (and i did get pulled over a few times and used that trick to my advantage)

the only problem, is it doesnt sound as "nice" as most exhaust systems. as for now, i am having my catless ecutout system put onto my ebay catback, so it will have that deep smoothe boxer rumble, then that loud as crap setup i need sometimes.

wish i never went back to stock.....
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Old 04-18-2008, 02:37 AM   #11
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Alot of people confuse exhaust with power loss or gain by sound, with turbo less backpressure def. better with bigger exhaust or open down pipe. some actually buy a valve that opens on exaust at downpipe so u get open when you want to race but stock when you want peice and quiet daily driving.

But remember its getting warmer so turbo doesnt work as well as it does in the winter.
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Old 04-18-2008, 02:40 AM   #12
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yeah I just put a QTP on mine a couple weeks ago.

very fun mod. pretty loud too, but yeah I close mine whenever theres a cop behind me too
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Old 04-18-2008, 02:40 AM   #13
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Quote:
Originally Posted by crzyazzpolak717 View Post
some actually buy a valve that opens on exaust at downpipe so u get open when you want to race but stock when you want peice and quiet daily driving.
that would be a cutout




**** double post
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Old 04-18-2008, 02:02 PM   #14
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I'll be getting a silencer made for the straight pipe for when I'm just driving around town. I will keep you all updated. I should be getting it in about a week.
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Old 04-18-2008, 04:34 PM   #15
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Quote:
Originally Posted by AWDPirate View Post
yeah I just put a QTP on mine a couple weeks ago.

very fun mod. pretty loud too, but yeah I close mine whenever theres a cop behind me too
my qtp broke twice over this winter. be wary. their customer service isnt the greatest by any means.
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Old 04-18-2008, 06:24 PM   #16
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howd it break?
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Old 04-18-2008, 08:56 PM   #17
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stuff got into the casing and locked up the gears. the first time it was salt from the roads and their only response to that was telling me to "be careful with it" after taking far too long to repair it.
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Old 04-19-2008, 06:21 PM   #18
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zero backpressure tuned right = less lag with more power across the band

zero backpressure w/o proper tune = powerband shifter up and right
[w/o tuning, the ECU will learn its way back to compensate]

I have a 3" catless DP w/ Badlanz cutout to stock catback. It seems to have more torque closed and more hp open..... don't ask me to explain that though.
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Old 05-02-2008, 02:04 PM   #19
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Old 05-02-2008, 02:04 PM   #20
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that was a stock sti ^^^with a qtp downpipe with cutout open
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Old 05-02-2008, 02:43 PM   #21
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Quote:
Originally Posted by Giganticprune View Post
stuff got into the casing and locked up the gears. the first time it was salt from the roads and their only response to that was telling me to "be careful with it" after taking far too long to repair it.
just updating this. the second time it broke they did end up taking care of me. i guess they had issues with the first service guy or something. i would just reccomend taking the unit off in the winter...if you were to do a QTP cutout
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Old 05-02-2008, 02:46 PM   #22
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Quote:
Originally Posted by QTP View Post
that was a stock sti ^^^with a qtp downpipe with cutout open
Wouldn't one see similar results from just a TBE with minimal to no mods? I would like to see that cutout vs. a 3" TBE.
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Old 05-02-2008, 04:03 PM   #23
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after reading this thread, i need a little clarifying..

so if open downpipe/straight pipe/no muffler/etc is bettter, then why are some people on here claiming that their exhaust leak made them lose power? from what i am reading, a leak should mean less backpressure which means its suppose to be good, right?
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Old 05-02-2008, 04:11 PM   #24
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if you have a pre-turbo exhaust leak, you'll definitely lose power.
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Old 05-02-2008, 04:25 PM   #25
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but everything after the turbo is fine right?
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