[katsooba]

Hi,

sorry for the bump, but i noticed your calcs are pretty good, but you forgot one important thing about the cross sections of the pipe, which is flow restriction.

2 2.25" or 2.5" pipes will have more restriction friction wise on the flow, than a 3" or a 3.25" single pipe.

2 2.5 pipes have almost 2 times the friction of the 3.25" single pipe.

more friction = more heat, we dont like it, even if its on our exhaust.

im doing a 3.25" single midpipe soon,
if thats going to be hanging too low on the car ill just do a 3" midpipe.

i have a N55 engine with CP-E 5" downpipe [it was a bargain]