2.25 vs 2.5 pipes?

[momonapua2003]

i got a 99 gt with stock exhaust except the flowmaster 40s. the problem is that it isnt loud enough for me(im 17). i was wondering if going to 2.5 pipes with high flows cat will make it louder and about how much power will i gain from it or how much loss of torque will i lose. i got a cold air intake and pullys so im somewhere in the 280hp range. thanks alot

 

[UVBNHAD]

2.5'' will not effect your hp/tq negatively. You will see a small increase in rwhp/tq; maybe 10hp/20tq at the absolute most. It will be noticeably louder but I would go with an off-road midpipe unless you have to worry about emissions. Pro-chambers sound beautiful with Flowmasters or Flowpaths. I'd guess with your mods and if you put exhaust on there you would be in the high 240s to low 250s to the rear wheels.

 

[Tylerb59]

Best way to get louder is to change the mid pipe, and then your mufflers. No cats = LOUD.

The larger dimension tubing allows the engine to breathe better, and if anything sound wise it might echo a little different making it sound deeper ... not louder.

 

[TweekedGT]

Go with a prochamber and if you are going to change the mufflers go with a Magnaflow Magnapack catback, it is loud and sounds awesome. It's got a snarly sound to it.

 

[CManT1914]

Change out your mid-pipe, maybe for an o/r h-pipe. It will be a LOT louder then. And if that still doesn't quite cut it for you, then put on some dumps. That will make it REAL loud. You wouldn't even have to take your tailpipes off, you could just leave them on for the looks, and have the dumps on.

 

[Seraphitia102]

i changed my midpipes and catback with custom 2.5 in pipes to notice a difference in sound. It's a lot deeper now and it sounds like a truck.

And I'm using Flowmaster 40's street muffler, not delta flows.

 

[FalconGuy016]

10HP/20TQ ? I never heard of numbers that steep without headers

 

[wms004]

10HP/20TQ ? I never heard of numbers that steep without headers

rear wheel hp for catbacks are about 5hp and midpipes are about 7 peak for catted, and 9-10 for o/r.

 

[twogts4us]

If you want louder, go with an O/R pipe. A catted pipe will be a lil louder, deeper, but not much of a volume increase.

 

[hotmustang331]

Um actuall around 7-9 RWHP for catback, midpipe 5-15RWHP, LTs give another 10 or so.Full SLP exhuast gives 30-35RWHP, and I know SLP CB gives 9RWHP and SLP catted Xpipe gives a little over 10 RWHP ,so with the 2 afore mentioned exhaust mods a mag gained 19.5RWHP (with adverages taken, not peaks) So with LTs your looking at about 7-10HP or so extra for a total in the upper 20s to 30RWHP. And from what EVERYONE says it is VERY VERY loud, especially W/O cats. BTW if you havnt noticed these guys are VERY conservative (sp?) on HP ratings, and really for good reason MOST products do NOT deliver as advertised.I have personally read articles on dyno tests on both midpips and catbacks, as well as some shortie headers, so I pretty much know the adverage power gains.(they just dont want to get your hopes up, but I am not saying that my info is 100% correct, just what I have read) Like that mac CAI they claim 25RWHP but what they dont tell you is thats with the MAF and I am sure some tuning and taking the low of the base run vs the high of the after run in some cases...usually dont believe the manufactures claims, rely more on outside source's dyno tests. Hope this helps you and gives you a new way to look at these cars, claims, and mods.

 

[momonapua2003]

thanks alot guys, it really helps. the only prob is i live in southern cal were smog is the devil. i want that o/r h-pipe ur talkin about. is there anyways i can keep that on there and then clamp back on my cats when smog comes?

 

[UVBNHAD]

You can't do that because the cats are welded into the pipe itself. If you are technically savvy you can hang onto your stock pipe and when you know that it's time to go in for testing swap the pipes out the weekend before you go it.

 

[wms004]

You can't do that because the cats are welded into the pipe itself. If you are technically savvy you can hang onto your stock pipe and when you know that it's time to go in for testing swap the pipes out the weekend before you go it.

he just needs to bolt up the stock H for smog check.. not too hard

 

[hotmustang331]

OR run the slp catted X, it comes with cats and they can be replaced with SLPs race pipes...cats simply clamp inline, then after the test/inspection unclamp and replace with the $60 race pipes.Or you could do like the afore mentioned (like I am doing) and keep the stock H and swap it once a year...slp way is easier though.