I dont think increasing the bore in b6 would be worth it.
There isn't much room to fit a bigger piston, as the b6 actually in itself is a stroker. You would need to get new sleeves made if you decided to do it. Alot of people who do put in the bigger pistons are generally All Motor applications, anyone who does Turbo stuff generally just ops for the BP since its so much better.
I do recommend a adjustable cam gear but only if you get Megasquirt or another ECU I dont think Rocket is able to tune for that.
This is just my opinion, Rocket and the rest of the Gang will most likely agree.