I have a 98 Trail Blazer, Dg exhaust, uni filter, HPD clutch kit(on the way),
Would like some advice on the difference when shaving flywheel?
If so how much would I take off???

 

With the shaved flywheel the engine will rev quicker.
You pretty much have two choice with how much to take off.
Decide if you want to keep the electric starter or not.
When you send it to get shaved, I sent mine to HPD, he will take
off the amount to keep electric start and the amount if you get rid
of electric start.
The exact ounces I dont know.

 

With the lighter flywheel how does that effect idling?

 

It doesnt if your bike is tuned correctly