I finally gave up and went with the M Performance black chrome tips. Since I was adding the carbon fiber diffuser at the same time, it actually looks better without so much CF back there. I left the black tips extended out about 1/2 inch beyond furthest inward position for a slightly more aggressive look, and it looks great! (I riveted the tips to the exhaust pipe with steel rivets to keep them from loosening; it's the OCD in me!).
