How crucial is the overpipe?
 

Looking at Perrin's testing, seems like there could be an improvement to be gained w/ an overpipe, but I'm not sure it's required for my application. I just got my '14 BRZ, and will be getting EcuTek w/ the Delicious stage 2 map next week.

Planned mods:
KN panel filter
JDL headers
Ti axelback exhaust

Questions:

Headers:
I just found out that the stock headers are EL... so why switch to UEL besides the sound? I know there's a debate between the two, but if it's not much of a difference, I think I'll go with EL to keep the stock sound which I like. However, I'm thinking about just getting the headers uncoated, then wrapping w/ thermal wrap.

Overpipe:
Necessary for the Delicious stage 2 tune on 93 octane? I think the tune it w/ a stock overpipe, but if this pc isn't that much, why not?

Midpipe:
main reason for keeping stock midpipe is sound. I really don't want any droning or excessively loud exhaust sounds, especially at low RPMs. That's the main problem with all the catback systems I see... the ones that sound nice to me (Tommy Kaira) are overpriced. I don't want to be setting off alarms or waking people up when I come home late at night.

Muffler:
Might keep stock, or might get Ti system for weight savings. But, same issue as above (sound levels and droning).

Well first off the one thing you never address is what your goals are. So this makes it kind of difficult to guess where your going with things as it sounds like you want to switch out the header and retain the stock exhaust. Sounds kind of odd to spend that much money on tuning and improvements only to keep the stock exhaust. Second the stock header is actually UEL...it's just not too drastic as aftermarket where you actually notice. If sound is your concern there is a few options out there for keeping the exhaust quiet. If you're already spending that much you might as well get a full exhaust..

:D

haha, no.

Ugh, I am no t used to starting off in a new forum and explaining things from step one. sorry about that.

Goals... get rid of the tq dip, and overall more power while still being a DD.

How restrictive is the stock exhaust though? I'll only be retaining it until I find one that I like, so it's mostly a temporary thing. I had an STi w/ full race pipes in the past, and that was one mean machine, but loud as hell. Did plenty of track days as well (circuit and rally, not drag).

http://blog.perrinperformance.com/br...n-and-proving/
This picture makes the stock part look like EL headers... but they're actually slightly UEL? hmmm, interesting.

In any case, I don't mind a 10% difference in hp gain if I can keep the sound increase to a minimum, hence keeping the stock exhaust while doing everything else first.

To be honest the minute you change your header it's going to get louder theres no way around that. In terms of the stock exhaust i'm not sure on how restrictive it is but i don't think its too excessive but again that's just a matter of opinion...although weight is a different story. You can keep the exhaust fairly quiet if you retain the two cats in your options of one being in the header itself and one in the front pipe. And then obviously choosing a exhaust that is resonated as well as having a decent muffler. You can piece it together and figure out what works best for you but if just the torque dip is your concern a tune can correct that easy...

To get rid of torque dip you'll need headers and a tune. Here's mine with P&L catted EL. Tuned by Moto Mike. You can see the torque dip is now the torque peak. I do have a Perrin OP and catted FP, anything after that is just noise maker. @aznatama

Thanks pche. That's what I've been wondering. So perhaps I should get a HF catted front pipe as well...

Do you have the catted header or catless header? I'm thinking catless UEL header, overpipe, and HF catted front pipe matched to factory muffler for now. Although the front pipe may have to wait a bit...

I have catted EL. Like you, I wanted to keep the volume at a minimum. I have stock mid pipe mated to Nameless 5" axle back. EL headers are always gonna make more power than UEL, although the difference is minuscule. So if you like the sound of a "boxer" get the UEL, the trade off is that it will be louder, and raspier-which I personally can't stand.

pche, do you have a sound clip of your setup? Also, did you do the header and axle back at the same time?

Thanks!

replace the overpipe last. its not that restrictive compared to the cats in the header and front pipe.

Save your $$, go FI

Nah, not very tech savy so I don't even know how to post a sound link lol, plus my phone is the only recording device I own.

I did the axle back with front pipe, then headers with OP. The base line in my dyno chart is with all the exhaust bolt ons, as you can see, it yield pretty much no gain without a tune. So if I were you, I'd gather all my parts first then get it tuned ASAP.

I will have the EcuTek w/ the stage 2 map, which should be fine for now.

I don't think I'll do much more than that for now. Not going to go FI since it's a daily. If I go FI, it'll need a LOT more upgrades to internals and drivetrain to be reliable, which is $$$$.

I got the ECUTek as well, love it. I have 4 maps that I can switch on the fly, plus launch control, flat foot shifting and auto rev match down shift. Best tuning platform IMHO.

I too had a big HP WRX, a 07 "STI wagon" (rotated GT35, 6 speed swap). It was my pride and joy but it was also temperamental and cost a fortune to drive at 9mpg. I rather use my 185whp all the time than the 435whp carefully in a straight line.