Aircraft engineer's and hot-rodder's have been experimenting with the concept for decades. Risingsunn and I fooled around with the idea while building a new exhaust for his mark2. We found just the opposite was true... The longer the pipe in front of the expansion chamber the more top end power was created and the more low end power was lost. I solved the leakage problem. The problem I couldn't solve is "space", as in not enough of it to allow a long enough internal pipe room to slide in and out of the "J pipe" to make any appreciable difference in performance...
However it was a good way to gage how long I wanted my exhaust pipe. The day after we finished the mark2 pipe I shortened the pipe on my rattletrap by 6 1/2 inches in front of the chamber. I gained significant low end power and didn't sacrifice any top end power. I then reworked the curve as the pipe exits the header. I actually added 4 new twists to the "j pipe" before it enters the expansion chamber and gained even more low end torque without sacrificing any top end power.
