How much Horsepower are you making?

couldn't you get close with a temp gun on the primary next to the head? It would save the average guy a huge expense on egt probes.

No. Going with the extent of your twin turbo build, I'd pitch the DSP with a/f tuning in favor a standalone. One lean cylinder and game over. Engine failure's happen's VERY fast with high boost. EGT's and cylinder timing per cylinder are the only way to tune.