TBH it isnt really worth tuning the 1.3, although I have seen bike carbs fiited, you'll need a suitable pair (suxuki gsxr 750 ones are used quite often) and a suitable ecu will be needed, which will turn it into quite an expensive conversion, I haven't been able to find a 4 branch exhaust manifold for them so it doesn't look good on that front, although there are exhaust systems available for them. TBH the only thing I really recommend for the 1.3 is a decent panel filter and a cat back exhaust system, any other mods will be really expensive and you wont gain fuck all from them, a bigger engine would be a far better move.