Suggestion- How much mileage on the teg? If the mileage is high a compression leakdown test wouldn't hurt, to be on the safe side. Yeah your forgeting to upgrade the internals. That's what I notice with turbo setups these days, most people don't upgrade the engine as a whole. I wouldn't expect it anyways seeing that he's going with a custom kit.

Turbo & intercooler sizing is pretty important. I'd probably look into upgrading the exhaust system ASAP. Just my 2cents!
Doubt any of it was helpful.