De-restrict, which should net you high fifties hp, and cost pennies to achieve - assuming we're talking anything other than MC28.
Spend the money on genuine parts, and a dyno setup if there's one about.
Keep the airbox and filter, nothing filters as well as that, and anything going into the crankcase that isn't petrol air or oil is gonna shorten the life of the crank.
Fit decent new tyres, and service the brakes.
If you have spare cash, then get the suspension overhauled - start with the front. If you can't afford it, then at least get some fresh oil in there.
That help any?
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball
