Hey Rics,
I am not a pro in biking. But to my knowledge One of my friend has done bit Mods to his Blue r15.
And it really looks cool.

1. He got his stock rear tyre fitted to front.
2. He got a Rear tyre of Kawasaki ninja of IRC soft compound 130 section to the rear. It costs around 3-3.2k
3. He got a back seat cowl, to make the bike look single seater. Rs. 2k
4. He got the tail light done with a spray paint job and now its given the shape of r1 tail light.

5. He has got the air filter changed to a pipercross. And now his bike makes a nice roaring sound. It costs around 2k with proper jetting.
6. Now his R15 is become more attractuve and also there is no loss of power. And it terms of handling the bike still remains smooth even if the Speedometer show 140+ kmph.

He has got the tyre change done in grant road, Mumbai. And got the air filters done at Borivali.

If I get a chance I shall upload some pics of his bike.