Bob, If it's a Dynomax system, it's 2 1/4" Bob (BB-NYC '89) Date: Thu, 28 Oct 2004 12:34:00 -0400 Subject: [Shotimes] catback system Ed I just paid $360 for a catback system (I beleive it had dynomax mufflers) from FPS in Georgia. While I thought it was 2 1/2 inches in diameter, I beleive that someone said that they may be 2 1/4 inches in part of the system Bob