Load , warranty, despite 20hp more power which i guess not will be the case, stock 1.8 will easily beat u due to your high rolling resistance upsized tyres.
Fuel economy will also be hurt.
Brotherly advise remain away from all this stuff....
Even having Turbo i am having BGs, conservatively speaking they are not that much bad either. The price difference and what you get in exchange is not justified.
That was true for Euro stars but i think not in case of BGs. Rather than prolonging extra miles on an imported double priced tyres its better to replace BGs at 30k kms.
For your info all makes of tyres becomes some what hard after 40k kms so why to spend more.
But if your pocket allows, go for the original or get the right size with tyre upsize calculator not to get the deviation above 3% otherwise the essence and quality of ride will be compromized.