does anyone know how much horsepower and torquea single cut out past the Y-pipe on my 1995 z28 (dual cat)would give me? My mods are a K&N CAI, JET air foil, and a 2.5" Flowmaster catback. I was reading that the flowmaster catbacks are one of the worst free flowing catbacks you can buy. is this true? one guy claimed from a dyno that his car gained 9hp with the cut out oper over the cut out closed going through the flows. and some other people claim of seeing some cars gaining 20hp on a dyno. thx

 

No way are you going to get 20 RWHP just from a cut-out. I'd say you're looking at around 5 depending on where you put it. If you have 2 of them, one on each branch of the Y pipe I could see a little more, but if you have one cutout I'd say 5 on a stock motor.

 

it depends on how free flowing your exhaust is. if you have headers you will get better gains than if not

 

just got it installed today and it sounds mean. but do u know if i would gain 5rwhp over my flowmasters? thx

 

Once again, theoretically you should gain a little over the Flowmasters because you're bypassing a lot of tubing as well as the muffler, but you'd have to dyno it to actually find out.

 

Im not sure you would gain any power really. Maybe you would gain a bit of peak horsepower, but I would imagine you would also lose a bunch of torque due to the huge decrease in backpressure. You are talking about essentially running open headers on a basically stock 350- not neccessary at all. I think the loss in torque would actually make your car feel less powerful if anything, although I'm sure it will be loud; if that is your ultimate goal.

 

ya i dont think im losing much back pressure since i had the cut out put on past the y-pipe where both cats are. its probly a 6 inches away from where the pipe goes over the rear axle. correct me if im wrong but i dont think i would lose much back pressure from that.

 

im gonna hijack this thread...
and ask how much HP ill gain from a completely stock to a cold air intake and catback exhaust? jw.

 

Z28 Kid, at that point in the system you're not going to lose any backpressure, but you're also not bypassing much except the muffler, so you're not going to gain much HP at all.

th3po1son, advertised HP 30, actual HP probably around 10-15 or so.

 

ya my main goal was to make my car louder not to really increase hp