Originally Posted by Sideways,May 5 2008, 04:59 AM

I had a Random Technologies 4 inch cat necked down to 70mm. It was a nice looking piece but somewhere in the last 800 miles it gave up the ghost. It didn't last 1000 miles.
The car was getting quieter, still very loud but quieter. On the dyno it lost 60 rwhp and my tuner said it has to be the cat. Sure enough.

These cats apparently are not able to handle the extreme flow from boosted S2000s.