Diamondback Drifter Chopper 2stroke Build

nice keep the pics coming
-briggsandstratton

ouch!!
drilling through the frame has been known to make the frame crack.
That bike looks similar to an occ chopper and on the occ you have to offset the engine to the left to get the chain to line up because of the fat rear tire.

sure, you can use copper for the exhaust.
the exhaust will get very hot, but not enough to melt the copper.
The joints may suffer tho, unless you braze or silver solder them together.
I'm not sure how well a copper exhaust will look tho, and if you don't run a muffler, be prepared for it to be SUPER loud.
like i said, that frame looks very similar to the occ frame, and there are exhsusts out there already made for the occ, that MIGHT bolt right on and fit your bike.
Or, you could buy a chrome long pipe with a muffler for around $30.00, and modify it to fit.

That's a cool looking bike, but i hope you plan on using something other than the engine kit supplied gas tank.