Having problems with my gti!! 1.8t?

First off, you should not be driving that fast unless it is at a track.

There are a lot of reasons for this. What were the weather conditions when you ran faster? Motors produce more power in 30 degree weather conditions than they do in 90 degree weather conditions.

You could have a combination of the following issues

1. Tire pressures could be low. Lower tire pressure create grip, but also create drag.

2. Check your air and or fuel filter. If either one is clogged or dirty that will cost you some power

3. Have you done a compression test? It is very possible that your motor could be wearing out and losing compression. As it loses compression it will lose power.

These are just a few suggestions.

I agree with the first guy. But also check the diaphragm on the boost control it cracks on the 1.8t and you will lose high end torque.