Originally I had a stock lq4 with a eBay 7875, caused to much back pressure and blew the motor after couple of months. But I did make 620whp on 91 and mainline dyno.
If I was to do this again, probably get a vs racing gen 3 7875.
I pulled another lq4 from the junkyard, going to keep it stock bottom end. Running the stage 2 cam again, 1600cc fid injectors, vs racing 85/88 t6 turbo, ls6 intake, 2x 450 fuel pumps, 50mm turbosmart wastegate. Made my own turbo piping.
I'll post a pic of my old setup and new, currently in the process of building it.
Has anyone ran the 85mm t6 vs racing turbo on stock 6l?

Also running a z32 5 speed transmission with fx1000 clutchmasters clutch. Held 620whp and 550tq. Going to test what the limit is on this thing.

Nice!
I'd be curious what really blew the engine. "Too much back pressure" is a new one on me...
Usually its lean out, detonate, bend a rod or blow a ring land type thing.