SI Muffler on DX?

He folks...I bought an '99 Si muffler today and I'm trying to put it on my '96 (same generation) DX. I've heard that it should bolt right on, but after measuring it initially, there's a 1/4 inch difference in the outside diameter of the piping of my stock exhaust system and the Si muffler piping that bolts to it.

Anyone done this? I will def. let you all know how it works after I figure it out...or if someone pipes (no pun) up and tells how it is before then L8R.