Flapper and Pair Valve mods?
I have heard people talking about the flapper mod, but what the heck is the pair valve mod? Also, do these mods add to performance or is it an opinion type thing. I have heard people say they do lots and also that they do nothing. I have a 2003 954 w/ a PCIII
and a Jardine RT-One slip-on. Do you guys think it is worth doing these mods and that I will gain performance? Any links to the Pair Valve one would be appreciated. Also, do these mods help shorten the life expectancy of the bike?