Mystery issue

[Soush]

So finally finished my truck.

2014 Sierra Single cab L83.
GPI stage 2 cam kit, DOD delete, LS7 lifters....
2.9L Whipple with a 4inch pulley
Stock convertor
Full exhaust
Tune
Got 517whp... Everything was running perfect untillll.... Started losing power, and quite a bit. Took it back to the garage, they tested pipes, vacuum, all seemed to be in order. Later found 3 spots where there were leaks im my exhaust where the headers connects to the y pipe and out the y pipe to the catback, they were clamped... So got flanges and bolted them on... All perfect... Still running 7.3psi high boost and its beginning to frustrate me. I also get rpm drops in 2nd gear at 4500 and above (this has been happening ever since i added the cams before having the supercharger) - doesn't happen everytime, but happens more often than not. 

Any suggestions? Any ideas?
Oh i also have a gear oil cooler installed... Recently serviced everything, gear oil, diff oil, engine oil, spark plugs, changed the wiring to the MSD and added a heat shield to be safe.... Something is wrong and its quite annoying. Note: its hot AF where im at - Dubai... Easily hits 45degrees C during the day with insane humidity levels...

Any feedback wld be helpful... Thanks

 

Im going for a compression test tomorrow to see if that is fine. 

[m3n00b]

Are you sure it's not heatsoak?

[Soush]

Im not exactly sure on the term but as far as cooling goes, ive upgraded the thermostat, completely serviced the radiator, coolant temperate stays on a safe side with an increase when im really pushing it, but that doesnt happen nowadays as its too hot... 

[truckguy82]

My guess, belt slippage or bypass valve staying open.

 

Also, the LT platform is rather difficult to tune and I’d imagine there isn’t too much gen v tuning experience circulating dubai or the eu period.