custom from an exhaust shop. buy a decent HKS muffler from ebay or somewhere online, and have the piping made at an exhaust shop for like 100-200 dollars. you wont notice a difference in power between that and some ******* ridiculous priced exhausts like iON (1300+ dollars). yea, over time the stainless exhausts will last longer, but ive had cheap wleded exhaust for about 1 1/2 years, no problems. even if you had to replace the WHOLE exhaust once, you would still save money.
just my opinion though.
just my opinion though.