can you use the stock converters with long tube headers?is there one on each side or two?i want the headers but dont want the car any louder than stock than it has to be.are the aftermarket converters that most header companies sale much louder than stock?
I'm betting you can't. At the very least, going with longtubes will require you to shorten the existing midpipe. If the part you have to cut off includes any of the factory cats ... and it almost certainly does ... then there's your answer. The easiest answer is to get a midpipe designed to fit the longtubes.
There are two cats under your '05, one on each side. No, you wont be able to use long tubes and the stock mid-pipes where the cats are. The cats are right behind the stock manifolds.
I suppose you could but the cats are going to hang down a long way. You should really put your car up on some ramps and take a look at the stock setup. I'd go with some shorty headers and an aftermarket x-pipe. I've got a bassanion mine that came with cats and with straight pipes. One of these days I'll get around to putting the straights on and checking the dyno but so far the catted pipes are plenty loud for me.