You can get great gains by modifying the stock single exhaust and spend very little money by doing so.
Replace the resonator with a Dynomax perforated core racing muffler, or straight pipe if you want it really loud, then swap out the rear muffler for a 40 series Deltaflow Flowmaster muffler. Replace the stub of pipe from the collector pipe to the cat as it knecks down to 2" on the non-SVTs, which should be 2.25" instead. You can also modify your stock Y-pipe with a better merge collector and find a few HP.
