I dont think they would fit without alot of work, The stock manifolds are considerably shorter than long tubes, The aftermarket pipes are not ment to run up alongside of the engine, They hook into the collector of the headers, which are at the back of the engine when installed. Personally, Your best bet is to save and get headers, then do the whole exhaust at once, I know its costly, but you wont end up spending money twice, and going through all the hassle. True duals are nice, but when you are feeding them with the stock manifolds They are not really being used to their potential. I recently seen a set of pacesetter lts go on craigslist for 100$. Another thing to consider is that headers greatly contribute to the sound of the exhaust. as far as mufflers there is a link somewhere that has multiple sound bites of different mufflers so you can get an idea. Hope this helps