[TXAustin]

hey guys needs some help. when im in 5th gear and roll on the throttle making my way to full throttle(to prevent downshifting) my turbo sounds like it all of a sudden takes off and spools like crazy around 80 mph once she really gets going. it will also does the same in 4th with tow/haul on under the same type of acceleration. does anyone know what this might be? thanks again

First off, you have a 48RE. The 4 stands for 4speed, not 5. Tow/haul is 3rd gear.

From what you described I don't know what the problem is. Your turbo spools up and you go faster...:confused013:

 

[TXAustin]

The turbo will start to spool up then REALLY spool up fast. That part is normal. On a VGT turbo it constantly spools up and does not have this effect as bad.

Just wait till you drive in a truck with a larger/laggy turbo. Once that sucker lights it is insane! Basically times what you are feeling by 10.

 

[TXAustin]

VGT(Variable geometry turbo) is on the 6.7l Cummins only, no 5.9 has it stock and are really not much more efficent IMO. It does have a huge decrease in lag though.