Gutted Header & Front Pipe - Dyno Inside

[D_Thissen]

Any sound clips?

[Joe-G]

Originally Posted by redlined600

It has been my assertation that the stock header with the cat removed would be as good as any sub $700 header.

Here is the one I made by welding in a collector where the cat was. More pics in my build thread if anyone is interested.


That said I can't imagine a gutted cat is good for exhaust velocity.

Thanks for putting this on a dyno.

Nice! If I had the skills, I would have probably done the same. Wishing I took pictures, but the gutted cats definitely don't promote smooth laminar flow. The transitions in the header/FP after the cat is terrible.

But if you're in the business of paying someone to remove your header/fp, cut out, and replace your cats with pipe, then you may as well buy a budget header/fp. It'll probably cost the same. The car will benefit from slightly bigger diameter tubing as well.

That being said, I'm out a couple hours worth of work and my wallet is untouched, but I've netted a couple ponies and a few ft-lbs. Worth it in my books...

[Joe-G]

Originally Posted by D_Thissen

Any sound clips?

I'll try and get some later today if that helps? But I find recordings don't really come close to what most exhausts sound like in person.

[Plxdjake89]

Originally Posted by Joe-G

I'll try and get some later today if that helps? But I find recordings don't really come close to what most exhausts sound like in person.

Ever get those clips?

[Joe-G]

Originally Posted by Plxdjake89

Ever get those clips?

I used a Hero 3 to try and record the sound just now... It doesn't sound as good as it does in person...

Custom muffler delete, and both cats are gutted.

Video shows cold start, idle, minor blips, and banging off 4k launch control.

[ame="https://www.youtube.com/watch?v=IbA_jWi88ws"]FRS Exhaust - Gutted Header, Front Pipe, & Muffler Delete - YouTube[/ame]

[Plxdjake89]

Good looks bro, I haven't heard it yet but I'll take a listen a little later.

[Somerandom18]

Wonder how the 2017 revised manifold will do if gutted.

Sent from my Pixel XL using Tapatalk

[Andyxin]

is it possible to weld a high flow cat on stock header?

[churchx]

Yes, but why? Unlike with just gutting it you'll get smaller performance gains, and added costs of buying cat and paying for welding work will nullify cheapness bit. And even if primary cat in header is HF one, you won't be 100% safe from seeing cat readiness CELs. If you are ok with doing something to stock cats, aftermarket header with HF cat or even catless aftermarket header will be better choice (one stock secondary cat should be sufficient to pass smog tests, if those don't include visual checks).

[bfrank1972]

Originally Posted by churchx

Yes, but why? Unlike with just gutting it you'll get smaller performance gains, and added costs of buying cat and paying for welding work will nullify cheapness bit. And even if primary cat in header is HF one, you won't be 100% safe from seeing cat readiness CELs. If you are ok with doing something to stock cats, aftermarket header with HF cat or even catless aftermarket header will be better choice (one stock secondary cat should be sufficient to pass smog tests, if those don't include visual checks).

Yeah the only reason I can see to gut the stock cat (aside from just for the sake of science) is for those looking to remove one of the major restrictions in our exhaust with basically no cost (other than tuning, which is a given in my book). You'd be much better off finding a proper aftermarket header with a cat if you're worried about emissions impact or noise. If you're looking to stay legal, *any* mods you do won't pass visual (unless you fool them by just gutting the cat and leaving the cat shell intact).

[NJ10]

I plan on doing this, but have sourced a cheap OP and Berk HFC FP to go along with the gutted stock header. I am a complete noob in terms of tuning, would it be safe to assume an OFT OTS EL 93 octane tune would be a good starting point for this setup?

My primary use would be for autocrossing

[churchx]

I guess you can use OFT Stage 2 EL tune with gutted stock header, which, while not completely, is EL header, and Stage 2 tunes are for catless headers.

[guybo]

I've been gutted on Stage 2 OTS 93 tune since last summer. No probs

[guybo]

I just found this article. Interesting read on gutting the cats.

http://www.circuitmotorsports-blog.c...-fr-s-86s.html

Power modifications for this class are very limited, basically restricted to an air filter, catback exhaust, and the allowances of a gutted cat. The rest of the mods and work are all in the chassis and safety systems.

Yes, in this series, they only allow you to gut the cats, not use an aftermarket header. You can have an aftermarket catback

Surprisingly, even with the factory header and overpipe/front-pipe in place, the absence of the main cat made a big difference in flow. Most stock header cars we tune with an intake and exhaust are around 185-190whp. A header being required to reach or exceed the coveted 200whp mark. The race prepped FR-Ss we tuned for Dynasty all made over 200whp, we were pleased!

They tuned with Ecutek