4.8 exhaust tip questions

[yamaboy2000]

I want to install/buy a couple of the 4.8 style oval exhaust tips for my 3.0, however Im not sure where to purchase them, are most people on this board using oem tips(my dealer says $240 each) or after market/ebay ones?? And Either way can someone get me the exact dimensions of the oem 4.8 tips?? Also I noticed that it appears that the rear plastic fascia is different on the v8's, it seems to me that the removable exhaust flange on the 3.0 is a large round as opposed to an oval, is this true or just an illusion?? Any help is much appreciated as a local muffler shop is planning on installing some 5.5" X 3" X 9"(projection/length) tips on wednsday but the ones peeps have on this board seem to look alot better to me...