I did alot of reseach on silencer's this past week. Now I have a 2002 xc 600, I ended up going with Slp for 217.00. Now they claim there is an 8lb reduction in weight & a 2-3 hp increase. Alot of people you talk have different views about them especially on the performance gains. I read a guys test results from a 2001 xc 600 with the Slp & he said there was definately better throttle response. Most of the gain from low to mid range. ( I should note this guy was comparing the Slp,MBPR,PPP,&Dynoport Canisters ) Out of the 4 of them he liked the sound of the Slp the best, He said it wasn't to loud & sounded good though out the power band. If loud is what you want then go with the MBPR. The Slp comes HPC coated ( polished aluminum ). I ordered mine from Dennis Kirk. Overall I pretty much bought mine for the sound & the looks since my manifold and pipe are HPC coated.
Good Luck!
Let It Snow!!!!