Originally Posted by matt goodson
99% sure its the piston seal, parachute seals suffer from power drop when hot. O ring seals are not nearly so badly effected, so you could try having it converted.
The conversion needs to be done well, the crush on the O ring needs to be quite small and the comp tube needs to be a good one, given a high polish.
Lube with something like krytox 105 oil which wont combust.
Alternately I have been experimenting with running parachute seals on dry graphite (no grease), so far temp variation looks to be reduced, but its early days and I need to test more.
I have done a lot of o ring pistons, I don't polish the comp tube tried it both ways and there is no difference, the original finish holds the lube better, in my opinion