Welcome
The next upgrade you want is a Nelson Tune 
That will really wake that 4.8 up.
Man, these 4.8s are really coming out of the wood works now.
FOR ALL YOUR WHEEL, TIRE, AND ACCESSORY NEEDS
CONTACT: EPLEY'S TOUCH OF CLASSIC 1-270-843-6892
OR TO GET ME PERSONALLY CALL: 1-615-943-6514
2000 Chevy Silverado 4.8L RCSB: smoked UPD, Flowmaster exhaust, De-screened MAF, Nelson 93 hot tune. Upcoming installs: trans-go shift kit, Eaton posi, billet servo, ported and polished throttle body...Near future: 6.0/4L80E install with 150 wet shot