I am thinking about having a H pipe installed on my car and I want to know if there will be a benefit. The 327 is basically stock including factoy 4 bbl intake and exhaust manifolds with duel exhaust and Flowmaster mufflers. Will the H pipe help? If so what size hole do you drill in the pipes and what diameter tude do you weld over the holes? Can the pipe go anywhere in front of the mufflers? Thanks for any replies.

I installed an H-pipe 2.5" kit from Summit, at the time I had 2.5" pipe and 2.5" dynomax super turbo mufflers without tail pipes. I didn't notice any sound change or change in my 1/4 mile performance. I say don't waste your money.

X-pipes are supposed to work, I haven't tried one yet. Some of the Mustang guys say X-pipes sound like crap with chambered mufflers, like Flowmasters, I don't know if that is true. If an X-pipe does help, I bet it is less than .1 in 1/4.

JL's book says that they can be installed anywhere between the collectors and the mufflers. I had an "H" pipe installed later by the same shop who the exhaust. (They didn't charge too much more for the additional work) It is about 18" behind the collectors and is the same size as the exhaust pipes. If you are going to do it youself, you should make the holes as big as your exhaust pipes leaving enough room for a good weld. An "H" will make your ride quieter and you may feel a little more kick in the pants when you hit the gas. Rhat

dan,
i put a home made h-pipe under my 62 nova to quiet down the 3 chamber flowmasters. i used the same size tubing as the rest of the exhaust. located it right behind the 700 tranny.
it did help quiet things down and i believe it helped power a bit, seat of the pants feeling anyway. its a daily driver, no time slips on it to prove if its beneficial powerwise. soundwise it helped in my case.
good luck,
kip

I have the Dr Gas X-pipe installed behind my 700 tranny. I have 3" pipe going to Hooker Aero Chamber mufflers and over the axle. The 3" pipe I allowed myself to be talked into was probably overkill and is possibly hurting my low end torque.

That being said, everyone who happens to see the exhaust from underneath is impressed and the car feels peppier. As for the sound through the mufflers, it's very deep and throaty - it turns heads.

Ozzie

My brother installed an X pipe on his Rustang with Flowmasters and it sounds like a Honda with a fart pipe at low RPMs.

He agonized over whether to take the X pipe off because it was one of the ones with cats, so it was expensive. He wound up leaving it on, but is still unhappy with the sound.

i have an h pipe on my camaro, same size pipe as main exhaust. i'm confident it does help quiet things down as well as help low end a bit. not likely much, but a bit. funny to hear the negative thoughts on x pipes and flowmasters on mustangs. i'm running that exact set up on my 5 litre ragtop, (2.5 flows, dr gas x pipe) and it gets WAY more positive comments about its exhaust note than my camaro. even from my ford hating chevy buddies. it is truly amazing how many times i've had guys come up and say how good they think it sounds. it does also have shorty headers and a slightly lumpy cam, but i can't imagine they make that much difference. on it i went from an h pipe cofiguration to a dr gas x, and the sound definately changed, mellower at cruise, nastier when you mash the throttle, but at the track my e.t.'s seemed unaffected. maybe half a tenth, but not enough to really attribute to the exhaust change. oddly enough, seat of the pants feel was slightly up it seemed. anyway, just my experiences and .02