Installed this muffler on my 2003 Silvarado 6.0L V8, two 3" pipes downsized to 2.5" go into the muffler, two 2.5" pipes rear with 4 inch end pieces. The muffler sounds great, cold start sounds great, not too loud but when you sit on it that changes quickly. If you need to drive carefully you can make the exhaust quiet, but if you want noise it's very easy. Overall great sound, easy install, good price.