"and the car gets up to 100 and wants to keep going where the old carb would start to run out of breath"
er what gear is this in ?
Now all you need to scrounge up is a Y pipe of an EA82. I got my 4 speed up to 110 in 3rd after I fitted that Y pipe

Very kindly, let me add this info from another Forum, it might be helpful...Silverbullet wrote:... I don't think I've seen a definitive "How to" thread on the Weber conversion...