I heard that adding an h-pipe is good for 15 hp. Is this true? Is it worth the time and effort? Also, does it matter how far back from the collectors it is placed? Would it be too far back it where installed under the tailshaft of the trans? Thanks

Connecting the exhaust pipes does increase the scavaging effect which draws more intake charge into the cylinder increasing upper rpm horsepower. H-pipes are good but I'm convinced that the X-pipes work the best. These pipes are basically simiesed pipes about the location of the tail shaft. Dr. Gas (Sandy, UT I think) has these pipes and install kits. I've also seen these pipes in the Summit catalogs.

Joseph

Thanks for your feedback, Joseph.

Not only is the H/X-pipe good for horsepower, it will also make the exhaust system quieter. I had a 2.5 inch system with Flowmasters without an H-pipe and it was deafening after a couple of hours on the highway (3.73s in rear, so I run about 3300 RPM at 70 MPH). Adding the H-pipe made it much more bearable.