Well, there are a few and if you search through some of the older threads you will find them all.
First and foremost: A performance tune FROM A REPUTABLE TUNER will really wake up the performance of the QC (not nearly as much on the RC). Night & Day difference! Fun factor around 250% over stock.
The oil cooler lines have been known to leak- Take them off and take them to an industrial hose shop to have some built or buy online.
The "top" Power Steering hose fittings have been know to leak (see above remedial). I preferred the results of using a hose shop on my personal truck instead of going aftermarket.
The 48RE Automatic is marginal and adding engine power will make them ill. If they start to act up, don't waste your money on a fluid/filter change and or band adjustment as that very rarely helps. The screens in the Solenoids are physically small and the screen itself is so fine it would be considered impenetrable by a mosquito.
The GM Solenoids have a much larger surface area. The problem lies in the fact that IF/WHEN the screens plug with band and/or clutch material, they starve the valve body, line pressure drops and things go south from there very quickly. A deep-pan WITHOUT the filter pickup extension is a good idea and hopefully any clutch/band debris will fall to the bottom of the pan and stay there.
A "cold" air kit: Hmmmm... not so cold. Look at the design from the factory: They actually pull air from the grille and not from under the hood. Use a K&N drop-in if you like, in the stock filter box.
More info on here if you have more questions, post up.
The site is very slow but there are still a few hanging around.
My thoughts, opinions...
Ronnie