I dynoed my 03 ECSB 4.8 3.42(4.10 in two days) and I hit 252rwhp.
My mods are FIPK2,FLows,93 Nelson Tune 0 TM,Transgo+vette servo,cooler
Before I took my filter off I hot 250 then 252 when I took it off! I was pretty happy and it was in the 90's and very humid here in Louisiana! Good luck man!!!!