In 2 years I've had 3 gearboxes and heads gone once.
After boring it out and having a 1.5 fitted it goes like a rocket. I kill my friends Sierra Cossie no doubt every time (Honest).
But very fun to drive, I've had 148mph but slowed as I couldn't control it after.
Ten squid says you have not had 148.. I have never heard so much tosh in all my life. So the 12 inch Metro wheels and rubber band tyres were fine at twice the normal Metro speed? How was the four speed box coping with that sort of speed? Or did you fit two together to make it an eight speed? Lucky the police did not see you driving at 148 or they the would have laughed at you.
Actually I am being harsh on you.. because it is possible to do nearly 150 due to the aerodynamic co-efficiency of the sleek shape.
ps Does it have go faster stripes? To make it go EVEN faster and aid stability, may I suggest fitting a huge stereo, spoiler and an extra set of wheels.
Turbos have 13" wheels, get it right. They're a lot wider and have a much high speed rating. Seeing as my tuned 1275 Clubman would crack 115mph (Autobahn, satnav based speed reading as well as car speedo), a tuned Metro turbo could exceed that with an increased rev range or a longer final drive ratio quite easily. That said, I think 148mph wasn't the actual speed reached! But you never know ;)
Gearbox and aerodynamic issues? The Mini Miglia cars (standard mini round-nose silhouette) reach race speeds of around 125/130mph on the straights, and they do just fine!
Not sure how it would get near 148. Stats say it's only 93bhp standard, which is a good amount for a small car. Compare it to a Saxo VTR with 100bhp, similar weight, and can only do 120, and they are geared for it.
I suppose the metro will be quicker than that since it's been bored out, but not much quicker.
And keeping up with a cossie sounds a bit... odd.