I picked up the SPT exhaust (again) today. Put it on and did an oil change. I really, really like how the flared tips look. I think the SPT, Nameless (small tips) and Greddy are the best looking exhausts. The single wall, straight cut tips just don't do it for me. The other rolled or double wall exhausts (that aren't quite as pronounced as the SPT) look OK, but I don't think as good.
I was also reminded how good the SPT sounds! It's very, very quiet at cruise. Close to stock. Definitely a lot quieter than the Q300. It is considerably louder than stock when you get on it, but not excessive. The tone is always deep and sounds great. I'm really happy to have it back on. Also good news is that baby loves it!
While I had them off, I measured the stock vs. SPT midpipe. Stock is 2 1/4" and SPT is 2 1/2". SPT has the midpipe go straight into the muffler. Saves about a foot of piping and a 90 degree and a 180 degree bend. I'm assuming this would all add up to slightly better flow, but probably doesn't make that much of a difference (since cat back's don't really seem to matter).