A g13BB wil push 31's fine.
This runs a G13BB.

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They're 35's.
Get the gearing right for the tyre size and the 1.3 is fine. Sure, a G16 is nice, but you'll need to regear the car for the tyres anyway, so I'd get the gearing right first and then if you're not happy then go to the G16.
More power isn't a substitute for incorrect gearing. With the revs 20% lower at any given road speed, even the torque of a G16 won't make it drive like it has stock tyres on it.
Steve.