I just picked up 3'' Cattman piping, everything except the muffler; I was running a Megan Racing 2.5'' My question is since I will be welding up the 3'' piping to my 2.5 muffler, will I see any gains in power since it will still output through the 2.5 or will it just be in sound only? Will also be adding Cattman 2nd Gens to the mix which Ill obviously have gains from those but I was wondering about the exhaust itself.

 

I would think that you would still see gains, but I'm not an expert so.

 

Mufflers sole purpose is to muffle sound. SOme say a straight through design muffler will yield a few HP but it is still mostly just for sound. Nobody puts on a muffler to gain HP, or shouldnt lol. The b-pipe is not terribly restrictive, so gains from a cat-back can range from 5-8hp. It is when you replace the entire exhaust with less restrictive components where the most gains are realized. The more modifications you do, the more beneficial a proper tune becomes. The stock ECU map is meant for the stock components

 

Thank you for that explaination. Well I always thought a 3" cattman exhaust was top of the line when it came to power; compared to my Megan that's the only reason I thought I would gain some horsepower.

 

u arent gonna see anything until u get a tune so dont get your hopes up.

Moncef went from a cattman 2.5 exhaust to a cattman 3" and pick up 8whp peak and mid range

 

i dont think youll see any gains while u have the 2.5" muffler. youll have 3" piping with a bottleneck at the end.

 

you will see minimal gains from a catback unless you do other exhaust work like headers which will allow you to gain a few more ponies.

Probably a decent rough estimate is...

catback 5hp
headers 10-15hp
catback + headers 20-25hp depending on size and style(and tune)

 

Look who's the voice of reason these days. Well written, ShocknAwe.

 

Thanks guys! Gonna go see if I can give it a baseline Dyno now; install the cattman headers and piping and see what I come up with after with a tune.

 

Bigger piping basically gives you the ability to take advantage of available HP via the less restrictive 3" piping, it does not yield HP in and of itself. When you start throwing a ton a modifications at the stock ECU, which has no way to know what you have done nor take advantage of what you have done, it gets confused and scales things back. Cattman is one of the best you are correct on that. Get a simple piggyback unit like an Apexi SAFC and with the exhaust work you have done, assuming you have other mods as well, you could expect about a 15WHP gain. Might not sound like a bunch but you will feel it, trust me

 

If you dont have the piping yet, BRM exhausts will sell the piping kit for less money.

 

Well I think you will have some gains...It's similar to when I first with to a Cattman 2.5" catback and it was too loud for my taste, so I decided to remount the Oem rear muffler but to the Cattman 2.5" Bpipe and WOW! It was more linear, torque was up, throttle sensitivity was awesome as hell and I trapped a 2.1 sec/60ft....So I would think you should see some gains there but hopefully you're not gonna hate how it sounds, since the Megan Racing system uses a tiny 14" twin tipped rear muffler that's cute but not quiet at all...Good luck!

 

well the main reason i am upgrading is because i feel like my megan is quiet haha. at first it was a big upgrade from stock but now i feel like my ears have gotten so use to it; its almost oem sound . I've heard videos of the cattman headers plus 3'' piping to 2.5 muffler and it sounds mean. Excited for that haha.