Todd: Thanks for the additional info. Since I didn't know if the Hooker headers have a 3" or 3-1/2" OD collector, I ordered parts for slip connectors for both sizes. Worst case, I have used a local muffler shop for custom parts. (They just won't work on the car without cats.) Long term, I think slip connectors will wear out because I remove my headers regularly for experiments. (Crazy, but I seem to have become the 4L60E trans guru on ls1tech and I rebuilt my transmission several times a year to try different parts; and have to remove the passenger side header each time.) So something like a V-Clamp or ball flange would work better for me. Would you say that the Hooker Aero Chamber mufflers are quieter or louder than Flowmaster 40s? Newshool72: Thanks for your info too. My understanding is that the length of the collector built into the header is not as important as the length to the first reduction, if any. Ideally one should run full size to at least the X-over. I am running 3" all the way through. I didn't think about a 3" system being noisier than a 2-1/2" system as I am trying to quiet things down a bit from what I have. Hmmm. I am considering either quieter mufflers (Dunomax VT?) or installing glass packs before the muffers.