I looked all over Youtube last night for a older video of a four cylinder engine on a dyno. The exhaust was glowing red hot and as they speed up and slowed down you could see the exhaust pulses in each pipe. They would stay the same distance from each other and move up and down the pipe with rpm changes, they never bunched up.
So Radar, back to the question, What went wrong?
To big of pipe!
Step all the pipes down to 1 5/8" diameter, length 32"-35", collectors 2 1/2".
Joe
