5.3 to 6.0l Lq4 swap. HELP!!

Ok I have A 2001 1500 Z71 that had A 5.3l. Just bought the truck and wanted some more power, so I bought a cold air intake and took the truck to a local GM performance shop where they were going to DYNO tune it. Instead on the base line pull (1st pull) the truck pulled forward on the DYNO just enough to smoke the tires pretty good (little scary), truck made 215 rwhp afterwards they started the truck up and within 15 seconds it spun a bearing and locked up!!!!!!!!! So I swapped it out for a 2002 LQ4 6.0L. I took the truck back after engine swap, and they supposedly tuned it and they said the truck made 285 rwhp. My question is, for a 70 hp gain the truck sure does not feel like it picked up 70 hp. Sometimes the truck will scream, other times it wont get out of its own way. Please HELP!!!

There are a lot more question that need answered to get to the root of the problem if there is one. Bearing spun and locked up? Who did the tune? What are the mods?

mayhem motorsports Raleigh nc. The only mod was a kn cold air intake!! everything else 100% stock

Then the 2nd dyno is kinda high for a Z71. Something is amiss.

2,500$ later I have A truck that isnt to much faster than it was when I bought it ( 2 months ago).

well I did go from A 5.3 with 180,000 miles on it to A 6.0 with 120,000 miles, and a tune