Why is my top speed 70 mph?

I only read one post that said it dosen't have a Catalytic converter.It was not posted from ansonservice.That will be something we need to know,,,What type of exhaust Original? Aftermarket Duals? A cloged exhaust MAY cause this.Next would be fuel supply from the tank forward.We can make many suggestions.You need to injest all and get a starting point and elminate from there. Hard to give a solution by computer.Take your time,,,,, you will find it.When you do PLEASE tell us as it may help others in the future.