I bet mine would dyno higher with it open but it was the lower RPMs that killed me at the track... That is why I believe in track times vs dyno number...

Also my friend with a 6.0 runs better with his cutout open, I guess teh larger cube motors like a free flowing or non existant (cutout) exhaust system...

 

yep that's what I was gonna say. The 6.0 needs to breathe more. 4.8 doesn't make good torque down low so it probably needs some good backpressure.

 

mine likes it open and it's priceless to see the looks on people's faces when they hear that sound coming from a truck like this.

 

I totally agree with you... My 4.8 is pathetic on the low end, thank goodness for higher stall TQ converters....

 

yours is freak thou!!! Not to mention I bet your tuner is top notch, me not so bright on the tuning side....

 

mine runs the same open and closed....just sounds cooler open

 

6.0 swap is the only option. After you get it in you'll wonder WTF GM was even thinking with a 4.8L in a 5000lb brick

 

nawwww, I am not threw with the little guy yet!!!! Heads and a healthy shot of nitrous, should make it do well....

 

you should tried it more than once, it could of been anything? but it sure picked up mph which is a good sign....

 

Yep I will give it a shot next week.... GF said I can't go more than once a week to the track....