Originally Posted by M3takesNYC
I have an active xpipe/HFC with 2 resonators and my oem xpipe off the car and was comparing them. The AA has smaller diameter piping throughout the entire way. I didn't have a tape measure but used a string and marker. Need to find a ruler or measure but it appears the AA is 2.25inch piping and the OEM maybe 2.5 inch piping.
I am wondering if this is engineered to increase velocity or was it simply a matter of that small of a difference does not matter and 2.5 inch is much easier to get than the wier d2.75 inch bmw likes to use in other applications?
Our X-pipe is 2.5 inches measure from the outside of the pipe. The inside measurement is 2.3 inch.
We made a custom 3 inch x-pipe for a customers race car per his request and lost power. Bigger is not always better...