LS
I have been working on these motors for 4 years now. I'm amazed at the technology that can deliver 23-28MPG with 400-600HP, and 9-11 second track times in 3300-3600LB cars. Most investments are $4000-8000.00, as the heads, intakes, and related accessories are still up there in price. The Auto OD/6SPD trannies are pricey also. The diffs are comparable to the old school stuff, unless going to a sheetmetal 9". GM High Tech is the Bible of choice for good info.
The DR-LSX heads are stricly race and big cube at the flow numbers advertised-422-430CFM. We are hoping that Chevy comes out with a DR-LSX 330-380CFM head for the street guys. Most of todays heads are CNC'd for 330-360CFM-I, 240-260CFM-E, whether stock style or aftermarket.
The tuning is the issue today. There is a killing to be made if you can tune an EFI vehicle. I am being educated as I write.
The event of the year is the LSX Shootout-Oct, 15-18, in Memphis, Tn.
If you want to see Big Block killers in street form, this is the place. I still have a 540, but the LS motor has similar power and much better mileage, Damn-I never thought I'd say that in public!!
Good Luck, People!