Exhaust Question for the masses
 

Why do I not see anybody running an upgraded header as the only mod in the exhaust stream?

I've been running a JDL UEL header, K&N filter, and e85 with a self-customized OFT tune(mostly based on Shiv's and Wayno's contributions). No other exhaust or performance modifications. While I don't have numbers to back up the following speculation(Dyno or Decibel), I feel like it may still be true. :paddle:

Upgrading the header ONLY does a few things:
* increases flow in the more restrictive section of the exhaust
* allows the computer to run AVCS timings and advances suited to a UEL header
* does NOT drastically increase the volume of the exhaust, I honestly think minimally increases

The header combined with e85 and a tune make up what I have crowd-sourced to be the majority of power gains without going FI or heavier/internal modifications, hopefully pushing me up to something like 190-200 whp and totally removing the dreaded torque dip. I also see a lot of people wanting to make power but upset when their exhaust gets to be too loud.

So, why don't more people take the best of both worlds and free up their exhaust with a header but not pay the penalty of super-loud cat back/OP/FP combos? They also reap the benefit of improved drivability in the mid range without attracting undesirable attention.
:iono:

Just as some anecdotal evidence: I have several DataZap logs from OFT runs with 0-60 pulls in the upper 5.x second range and a couple 3rd gear pulls from 2500-7500. I strung some physics equations together with some mathematical gymnastics to calculate horsepower from these data points. :mad0259: Neither of these are true measurements of the force applied to the road, but they honestly ought not be too far off(a % or two) and they produce an upper WHP number right around 200.

Hopefully I don't start a flame war, I just wanted to share my experience and maybe hear back from others if they have observed something similar or if they think I am crazy.

Because race car :burnrubber:

On a serious note, I just installed a JDL UEL onto my brz. Only other mods being OFT and grimmspeed CAI. Had stock exhaust for 2 days and then I decided to throw on the nameless 2.5" track pipe that I bought before I even thought about a header. I honestly just wanted it to be a little louder then stock.

Just like you I haven't really touched anything else except for the axleback portion of my exhaust. Will be taking it to the dyno in the spring to see what it makes before/after a tune with a local tuner :cheers:

You mean like this?

[ame="https://www.youtube.com/watch?v=_LtCZLd1vKk"]Gruppe-S UEL Header and Stock Catback on Subaru BRZ - YouTube[/ame]

Hard acceleration at 6:15 and 12:05ish.

I have similar setup with- ofh, oft, e85 and a drop in filter. It is pretty silent, but now I am looking for more sound. Over pipe is going to be replaced, but I can't figure out what to do to get a little more sound. Still deciding between front pipes(catted,resonated,helmholtz resonator, straight through) for power or a catback exhaust for weight savings. Also considering getting an exhaust cutout.

If anyone has suggestions or sound clips, please post.

To answer you question, people buy exhaust for the race car sound and the shiny. Power/weight just happens to be a by product.

Ran just a OFH with stock exhaust and Tomei UEL with stock exhaust, i don't think it sounds all that great and by that I mean it sounds very close to stock, and stock out of the box doesn't sound that great to me, At least a header and axle back or just a catback sounds way nicer imo.

I definitely appreciate "Because racecar" and sound preference. I do find myself wanting just a touch more...aggression. But that doesn't really come without volume which I want to keep down.

I guess some part of me just wanted to get this option noticed a little bit more as I don't see it mentioned in the all-too-common "What exhaust should I get" threads which generally boils down to preference. I think stopping at this point provides almost all of the performance you are going to get.

Definitely the sound factor.. >_>

Speaking from my own personal experience: Theres a nice big 4 lane 2-way street near my house that I always drive down on my way back to my parking garage. The lights pretty much always line up and theres usually zero traffic in the direction that I'm heading when i got back home. So I love being able to start at a red light and then run first gear until 35MPH before I shift to 2nd and coast back down to the 25MPH speed limit.

This is also in NYC so I don't have to feel bad about waking people up since all the buildings along the street are commercial or condos.

The loud car also helps deter jaywalkers when I go through st marks, ktown, chinatown, etc. (other NYC members will know what I mean).

Any other times, especially if I'm driving through residential streets at night (in brooklyn and queens), I can just keep my noise down by shifting into 2nd early.

Agreed with sound factor.

http://www.ft86club.com/forums/showthread.php?t=81493

This article touches on different performance aspects of exhaust components, specifically cases like header no tune, header with tune and whether or not you have cats in the header. This is the article that inspired me to head down the cattless uel header with tune, leaving the rest of the factory exhaust as its not too too restrictive and wont increase performance significantly enough for daily driving. I feel like this route is a great bang for buck route without FI.(wont hurt for supercharger setups either though!) Highly recommend.

yea UEL basically tells them get back on the sidewalk lol

That sounds awesome as shit. Just a header huh? Nothing else at all?
I like that it doesn't go ping ping ping

No other exhaust mods. Running an OFT tune that got rid of the really loud cold start, but that doesn't really affect the sound when it's moving.

As others have said, sound. Also looks (2" tips in 4" cutouts is an eyesore). And once you've done header + CBE, you may as well do the rest.

If you don't mind me chiming in, if you get the jdl ultra quiet front pipe and pair it with an exhaust it should sound pretty damn good.