If you're talking about an engine swap, there isn't a bigger or more powerful one that goes in without major rework.

Edit:

This just in: Insurance quotes for some representative bikes.

'13 Triumph Street Triple: $276
'15 GSXR 750: $1260
'09 GSXR 600: $413

Looks like if I buy a GSXR 750 I'll have to make sure it's at least a few years old. This Street Triple is looking better all the time. Incidentally, the CSR accidentally looked up the same year Speed Triple (1050 cc triple instead of 675) and the insurance is the same.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.