I don't know if Wes frequents this forum any more, but he does have a dual exhaust that was custom fabricated for him at a reasonable cost. Here's an expert from Wes on another forum talking about his exhaust:

"With the baffles removed I lose some low end torque do to the lack of back pressure". But from around 2,800 rpm and up it nails you to the seat. For autocrossing losing low end torque is not a good thing. I have fabricated a set of baffles that are less restrictive (less back pressure than my "street" baffles but more than no baffles) that bring back the low end torque. With the baffles removed my times (autocrossing) were 1/2 second slower. With my "race" baffles in I am running about 1 second quicker than I was with stock exhaust. With the "street" baffles in it still has all of the low end torque but I lose some on the high end and no exhaust rumble inside the car. It's still a little better than it was with the stock exhaust. It's a tradeoff and with the race baffles I think I've achieved a happy medium.

To sum it up... The real reason to do this mod for me was more to make it sound better. And sound better it does! The performance gains are marginal... except at the high rpm range where there's a noticeable performance gain".