I run a 2001 YZ250 with a FMF SST pipe and a 'shorty' silencer, which is of course not forest legal. I looked into (i actually have one on order) a COBRA SPARKY bolt on spark arrestor. i really liked the idea of this item, since i can ride MX tracks without a big long silencer hanging out of the back of the bike and then i can bolt on the COBRA when i go to the desert. In addition, it only costs $55 rather than $125 for a complete new powercore II silencer.
But, i finally got a reply from FMF support and they said not to use the COBRA because it would cause loss of power (which also contradicts the claims of COBRA!).
i really like the set up of the COBRA system, and a small loss of power is not too big an issue for me since i only ride for fun.
does anyone have any experience or suggestions with these matters?? and will the bolt on COBRA cause any additional problems which would be a greater concern of mine (eg. messed up jetting or mechanical troubles etc.), or should i send the COBRA back and save up for the full powercore spark arrestor?
thanks in advance
bruce