Impressive power! A look at Leighton's website reveals the following mods, as well as Mark Dent's tune:

Harc-pro kit cylinders
Harc-pro kit heads
Harc-pro kit ECU
Harc-pro kit Gear position sensor
Harc-pro kit exhausts & silencers
Special modded airbox
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Rich
MC21 Track Bike / RS250 NF5 'Spencer', NX5 'Cadalora' & NXA 'Aoyama' / RS500 / Two Brothers Racing RC30