On my RecTec I'm cooking an 8 or so pound Pork shoulder and want to get a heavier bark, but still keep it moist. Normally I cook it for several hours then foil it for a couple more. (FTC method). Generally rub it with Worcestershire sauce and my home made rub. Basically the 321 approach cooking at 225°. But now I have a larger roast than normal.
Thinking of rubbing with maple syrup & my own rub, ,cooking at 225° for about 3 hours (IT of 175 or so), foiling it for 2 more, to maintain the moisture, then placing back on the grill, not in the foil, but open, and upping the temp to about 325° for another 45 minutes to an hour to get my bark.
Any thoughts?

Use butcher paper instead of foil as it will help keep the bark harder

Butcher paper will not burn? And am I on the right track about placing the roast bare back on the grill and upping the heat to 325 or so after in the paper?

Coat it with molasses or brown sugar.  Actually anything with sugar, real imitation maple syrup, honey, Karo...Once the desired bark is obtained, place in pan and cover to steam and loosen said hard bark!

Butcher paper will not burn? And am I on the right track about placing the roast bare back on the grill and upping the heat to 325 or so after in the paper?

It sounds like you have not used paper before. You need food grade butcher paper. It is usually pink.

Butcher paper will not burn? And am I on the right track about placing the roast bare back on the grill and upping the heat to 325 or so after in the paper?

I think if you use the butcher paper once you got your desired hardness of bark you will not need to put it back on the grill at 325.  The pink butcher paper will not burn at low temps unless you have a flame that hits it.  Do not use the paper that has wax on it.

Are you trying to get specific results with the bark?

You could go a little different direction and inject the butt prior to cooking to add some moisture if desired.  Then on the pit at 225 until it hits your desired internal, without wrapping in foil or butcher paper.  Produces a pretty dark and defined bark. 

I typically get a pretty heavy bark on my pork butts. I lightly coat the butt with a 50/50 combination of yellow mustard and Worcestershire before I add the rub. I then smoke at 170-180° to an IT of ~135° basting with apple juice every hour or so, raise the pit temperature to 225° and continue process to an IT of ~160°. Next I place the butt in a covered aluminum pan with a probe and finish in the oven to an IT of ~203°.

I actually coat with maple syrup and will spray frequently during the cook. Bark gets soft when I vac seal as the pork is very moist.

Lots of good suggestions for bark. But I would give yourself more than 5-6 hours for that 8 lb shoulder if you are planning on pulled pork.

But I would give yourself more than 5-6 hours for that 8 lb shoulder if you are planning on pulled pork.

+1