I have a 2001 Jetta, 96k. I bought this used around 9 months ago. It is a 4 cyclinder, manual transmission. Someone put aftermarket wheels and rims, 17 inch on it. I recently discovered the speedometer is off by 8mph. On the interstate, I think I'm running 80 but actually around 72-73mph. The motor is up to about 4000 RPM at 72-73mph. Is this normal. It really feels like the motor is having a hard time, I would hate to run it up to 80-85mph. Any suggestions, or is this normal.