OK I will debate it
The stock muffler does in fact go down to a 2.25 but the rest of the pipe before and after the muffler is 2.50 inches, you cut out the muffler and have a free flowing 2.50 system all the way back from the last cat I have nevre heard of any one running anything but a 2.50
Now back to you Surf!
Tom,
I cut my stock muffler off right at the muffler (with a sawzall) where the pipe has reduced to 2.25" and connected the Thrush at that point on both ends. 2.5" was too big, 2.25" was a perfect fit. Now if the stock muffler is reduced to 2.25" at the muffler, then another muffler with a 2.25" inlet and outlet should not only fit, but not effect exhaust flow any worse then the stock unit....it's hasn't on my Liberty, I actually got better throttle response, I'm getting better mileage, and it sounds good without being obnoxious.
Now, if you cut the stock pipe before the reduction in diameter, then you would be correct in that it is 2.5", for my particular application of installing the shorter in length Thrush, it just make sense to leave as much of the stock pipe in place as possible and utilize the 2.25" connections it left me....