They're machined 150 barrels, that bolt right onto the 250 cases.
No point trying to race it that way though, since if caught you'd be thrown out instantly - and what's the point in cheating to win? Not winning at all is it?
Spend your money on suspension first, then training, and finally on the engine.
Oh, assuming you've de-restricted it of course!
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MC21SP Plaything
BMW F800GS Bumblebee
Triumph 9551 Daytona Big boys toy
FJ1100 Sporting relic
GTS1000 oddball