Lots of threads on this. The factory 1.75 sleds do not have tunnel protectors, the consensus is they were removed to make room for the taller lugs. There is also minimal clearance for the heat exchanger. Basically everything I've read says don't stud a Nytro XTX 1.75, either because you can't or you shouldn't.
If someone was really set on doing it I'm fairly certain the tunnel protectors could be put back in, possibly with a Star suspension relocate to add some clearance. However I'm not certain if there is anyway to increase heat exchanger clearance without substantial modification/fabricating.