I have a 1969 chevelle 396 that I am going to but a new exhaust system. I have decide to either 40 series flowmasters with an H-pipe or 40 series muffler with exhaust dumps behind the headers. Both would have 3" tubing and the exhaust would exit before the rear tires to the side. How much power will I gain with the strait pipe set up? And how much power does the H-pipe give you, is it worth it?

an H pipe or an X pipe both will help,not sure on the numbers,but either are better than a straight exhaust,and an X pipe is slightly better than an H pipe.

with a 3" exhaust, on a little 396, would crossing the pipes really help all that much on the street?

The H and the X pipe will give you slightly more hp/torque,and will have a more "refined" sound,especially with the X.The straight pipes will be more lounder.

On my old 383 SBC that ran 7.30's in the 1/8th, I saw no performance gain going from straight pipes to adding an H-pipe. The entire system was 3" and used Straightline Performance "large case" mufflers.

The H-pipe did quiet the car down some as well as smooth out the sound of the idle.

If it going to quiet it down I am not going to do it. I want it to annoy people to be thats worth losing a few hp.

If it going to quiet it down I am not going to do it. I want it to annoy people to be thats worth losing a few hp.

I had the 2.5 flowmaster system with H pipe runnig the 3 chamber mufflers. Switched to 3" Torque Tech head pipes to the Dynomax ultraflows
kept the 2.5 flowmaster tails. This setup is much quieter in the car. With no step down at the headers and straight thru mufflers all the sound is behind the car, not in it. I could not believe the difference between setups, no interior resonance, nice performance sound at light throttle, really barks at WOT. Isn't that what we are looking for?

Originally posted by chevyblue:
If it going to quiet it down I am not going to do it. I want it to annoy people to be thats worth losing a few hp. If my mom would let me I'd run turndowns after the headers and call it good! I like setting off alarms in parking lots too. :D
Zac

"X" Pipe

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I went to an H-pipe when I redid my exhast. I wish I hadn't...
I thought I would keep it simple so I did straight 2 1/2 inch pipes from the header to the Hpipe then to thrush turbo mufflers then dumps before the axle.
It was louder and more choppy before but it kinda sounds cool. Real mellow. But I like it loud which is why I roll with open headers now.