kevs fuel mod will sort most of the surging and if you build your own like I did its very cheap to do. Upping your c0 setting also helps towards this, as does the cush drive rubber mod.
I've put k+n stage 1, dna stage 2, mtc cans, and kev fuel mod on mine and also carried out the air box mod and snorkel removel all in various stages.
Best power improvement per pound has to be the dna stage 2 filter.
Best sound improvement is the mtc's.
Happy modding, be warned though, it's addictive
