I like the 4" CORSA best of the 3 types on our rear exhaust Vipers....about a quarter of an inch of room on each side...bottom touches, but NO PROBLEM with heat as tips COOL, even in the summer heat here in Indy. I have helped other members install the CORSA cat-back on a 98 GTS, 2000 GTS, 2000 RT/10, and a 2001 GTS...same general fit in rear with only minor differences.
Tip : use duct tape to thoroughly cover the narrow fascia bar at the bottom of the exhaust exit opening BEFORE YOU TAKE OLD EXHAUST OFF TO AVOID SCRATCHING CHROME TIPS ON EITHER THE STOCK MUFFLER, OR THE EVEN BIGGER TIPS ON AN AFTERMARKET SYSTEM.