Here's some sneak shots inside a 21 pipe. There are basically two chambers between the stock outer 'shell' and the inner pipe itself. The chamber around the belly is a glass fibre wadding sandwich to absorb the sound, (only the L/H pipe has the mesh by the way) and the chamber around the baffle cone is open to the gas pulses via a small hole in the stinger. (lower pic...no wadding in this part) I just plated over the mesh and covered over the hole. No idea what racelines would do though.






Having done the work myself, £100 seems a bit steep, though it depends how much he charges for his labour I suppose, but only one pipe has the mesh remember. Though it did take a few hours, not to mention the stench of cutting through/welding sooty pipes

No idea of changes to power yet though, as Andy (being the busiest person I know ) has yet found the time to dyno them compared to a stock set.

(sorry if the pics are too big)