rex17

I want to try keep the main cats intact for emissions purposes. What kind of gains could I expect from an up-pipe and the Hush catback. I'm new to all this and also wanted to know if the up-pipe required any work done to the engine management system. Would the up-pipe be a senseless mod without a full turboback system to go with it.

myroncuz

iTrader: (20)

it'll be fine... maybe you should look for a dp with cat for optimal performance..

Wrxneffect

iTrader: (7)

Look for about a 20 hp gain at the wheels over stock. I have a STI up-pipe and a hush cat back. Stock I was putting 173 hp to wheels and now I'm putting 191 or 193, I don't have the dyno sheet on me right now so I'm not 100% sure.


Jason

WRX Rush

iTrader: (7)

I also have a STi Uppipe, and borla hush catback. Well I got sick of the borla being more restrictive than my tastes so I removed the resonator and I took the 2.5 inch flange and welded together a 3" flange. It is a wonderful exhaust now. Expect resonable gains after a few resets and 3rd gear tunes.

Cheers
Rush

myroncuz

iTrader: (20)

hey yo rush, is the hush really restrictive? also, how much is reasonable gains to you? did it get a lil louder?

damn dude, i never thought of gettin the resonator removed... thanks and mahalo yo

rex17

Thanks for the input, I would have no complaints gaining 20 hp at the wheels with that set up.

TroyBoy24

I have the 3" Borla Hush catback system running with a Helix Uppipe, I love it. Good hp gains and a wonderful sound all together. Still keeps the WRX boxer sound and the turbo spools SO NICE, lol
Troy

WRX Rush

iTrader: (7)

The hush (if you have an aftermarket downpipe that is 3") is kind of constrictive.

It has a 2.5 inch spin flange on it and then the exhaust is 3". The sound resonator (fiberglass and metal) is 17" long and can kill HP.

A really cheap fix that I am happy with because I love the sound of the hush is the $60 3" flange that bolts perfectly up to a aftermarket or stock downpipe (MPJ Performance for details)
Go to any exhaust shop to get a 3" stainless steel pipe welded in in place of the resonator.

Resonable gains was underestimating what exhaust can do for you (I was purturbed at the time) The gains you will see are about 20-25 HP across the board and really good torque gains across the power range. Yes the hush gets louder but keeps the low rumble sound at idle. And at redline it has a nice scream with a kind of porsche tone to her. I love it wouldn't trade it for the world.

Rush

myroncuz

iTrader: (20)

mahalo yo... will probably take that ouot....

rex17

Hey WRX rush I meant to ask you the other day, what did u mean by a few resets and 3rd gear tunes?

WRX Rush

iTrader: (7)

Resting your E.C.U. is a way to get all your engine management specs back to stock. Because over time a car will adjust itself for altitude, driving styles, fuel, ect. and by resetting it to stock specs it starts with a clean slate. To reset your car (you will lose any pre-sets for radio) Dis-connect the negative battery cable, pump the brake 4-5 times and re-attatch the negative battery cable. You now have a clean slate.

If you ever have watched or have had your car tuned, the tuners always start your car in 3rd gear at about 2,000RPMS. Hense 3rd gear tunes. Your ECU will adapt towards your mods (not completely but better than stock) if right after you reset your ECU you go and start in 3rd and go to redline. this will help the car a whole lot in the sense of your ECU being happy.

Good Luck
Rush

240sxer

i was also thinking about the helix up/down pipes with a hush exhuast... what about the helix exhuast?

WRX Rush

iTrader: (7)

I have the helix catted downpipe, it is a great piece of machinery and compared to the catless pipe your loss of 3 flywheel hp doesnt make a difference. And make sure the up-pipe is flex, anything else is trouble. Other than that they are beautifuly crafted parts. Cheers

Rush

t3ch9

iTrader: (5)

as far as emmissions, what up pipe and down pipe have free flowing cats?

WRX Rush

iTrader: (7)

Well. . . .

The up-pipe is known to the industry as a "pre-catalyst" and before the main catlytic convertors get heated up that is already changing the carbon monoxide chemically. That catyletic convertor only works about the first 4 to 6 minutes. And when they smog check your car it will already be heated up, so that will not affect anything. But do get one with a flex or you will have leak problems

As for downpipes, Helix has a downpipe that you only lose 2 hp from catless and race cat. I have that, it is a well manufactured piece. Although if you live in California it may not be enough to get past smog, so to get around that, take your stock exhaust go to any exhaust shop and have them weld in another catyletic convertor for somewhere around $150. Put that on right before smog check and you will be in like sin

Good Luck
Rush