It depends whats done to the car.

I would not get down the street to tune my gt35r rotated car, but i may let a that know that hes doing, but not proven himself tune my stage 2.

tuning for exhaust is pretty simple if you know what your doing.

remember there was a time that Snowman was considered unproven and many did not trust him.

I believe he tuned his own car, then mannys car, then niko's car etc. and now he is more proven.

I personally know a little about tuning, but its too much responsiblity tuning others cars.