I can remember when i got my Stg 2 DNA and Kev fuel mod (already had the Stg1) and it felt so much more smooth, powerfull and definiately wanted to play more with the sportsbikes!!!!
Just make sure you chain is adjusted properly and your cush drive rubbers are not knackered or are packed properly before changing just much on the KEV mod, ive found these needed changed more checked before i spent move anything on the KEV mod