[doogalman]

I tried the inserts after being pulled of the ring. Failed the noise test. I had to get hold of some steel wool and tightly wrap it around the insert and wire wrap around the wool to back the noise of further. A lot of arseing around to get out. The down side is that the marshalls get to know who you are.
My vote goes for the standard cans. If all vehicles ran race pipes the ring would be forced to close for ever to the public.

Doogalman