When I bought mine they had a jig on which they made the systems - basically a mock up of the LHS of a caterham complete with engine. I went with Powerspeed because it was cheaper and better finished than the Caterham equiv, though noise is proving a bit of a problem with mine (I have a R400 engine, and though freshly packed it will measure 96-97db, it is still loud on drive by - I was black flagged at Castle Coombe last time I was there). Some have gone for a rear exit system to improve the noise levels - basically another silencer hung across the back of the car.
TBH I think noise will be a problem with any tuned engine with the standard off the shelf systems
Edited by - davef on 15 Mar 2009 10:34:49