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Here's a picture of the quick fix to get past the limit at Barber in 2004. This was done at the track on Saturday. Yep, that's a brillo pad in there! First lap there were all sorts of sparks flying out the back!
Any way just to fab up curved tips that direct the sound away from the measuring station, as everyone does at Laguna?
The curved pipes and Suppertrapps can work (I have used both at Lime Rock on my car), but either by itself won't buy Chris several db in noise reduction, if that's what he needs. One data point worth sharing is that a friend of mine who has Phase 9's on a 964 was able to reduce noise by several db to run at Lime Rock by running the curved pipes and Supertrapps disks. That might do the trick for Chris, but I can't say it would be a sure-fire solution -- he might still fail a 103 db limit.
Another option I can suggest from my (limited) experience playing with mufflers and track noise limits, is a simple muffler like a Supertrapp (the body, not just the disks). The 4" ones are slim enough that you could run a pair of them in place of straight pipes in a car that doesn't have much room for mufflers. Those alone would probably make 103 db, and you could always add disks if necessary to lower the noise another couple db.
If you run Supertrapp disks, just make sure you have a large number of them (12-18), or you'll choke the engine.