Well the 460 with goodies is now in my 67 f100. I use 3 inch flexi tubing from the headers to the turbo mufflers and for a while ran it just as such. The noise was to noisey for my 69 year old ears so I had the local fellow bend and install the exhaust straight back from the turbo's. Where he made the bends it appears that the pipe diameter is more like 2 1/2 inch all things considered. I hear a H pipe is always a good idea but now I believe it is a must as I feel I lost some power in the process. Is it OK to place the HPipe either before or after the mufflers? Would scrapping the pipes and finding a place that will mandrel bend them a better starting point or will the H Pipe solve the problem? Thanks for any ideas.

 

You should place the h pipe as close to your headers as reasonably possible. The shop should have used 3 in pipe to exit the muffler, they created a resricktion in your exaust
Try the h pipe and the 3 in exaust from the muffler that should get you back to normal plus a little extra

 

The whole point of the H-Pipe is to create equilibrium in the escaping exhaust gases, balancing the flow and vacuum at the ports. Reducing it a little would not kill the back pressure, you need some restiction to create that vacuum at the valves. If not you can get cold sudden hot/cold gas flow and cause stress fractures at the valve. Gurus, correct me if I'm wrong-