Diesel gearbox are more reliable as people say.I how ever don't have a shred of evidence to back this up but I abuse my gearbox on the regs and it holds it fine.The question comes down to petrol boxes ie my mate had a mk2 fiesta with a 2 litre blacktop engine on 1.8 management and a 1.6 rst gearbox and all it did was spin and when it did grip I swear the speedo just flew round hit 140mph and carried on.We never found out what terminal speed was as there was no where to do.And with a mk2 fiesta being so dam light and not being caged or anything it was unsafe.So im think the ratios in the 1.3 are even shorter but would you lose top end speed.On another note from being in this mk2 fiesta I darnt think or should I say I carnt even begin to imgine what the hell a 2litre zetec turbo would do out there lol power to weight ratio wise.