I just got a $70 tip(I am tight with the dealer so I got it for 40). Ya seriously, I dont want to pay $1000 for a muffler that provides minimal improvement. Its all because Porsche had to make the crossovers inside a single muffler. I couldnt stand the tip so I knew I had to replace it. My only advice is a 1 inch bypass pipe, people give it a good review and its DIY if your fine with bending a little pipe and cutting holes, ive never heard this setup in person though. Or if I had lots of money I would by some valves so I could bypass the whole muffler with the turn of a knob, or find a good middle ground. Maybe someday.
http://www.dmhperformance.com/ecutout.htm