Aren't an '06 tt build and an '08 tt build going to net about similar hp? They use the same block, and both are typically overbored and then built up with forged parts. Don't you end up with basically the same engine except for the VVT? So, although it is a great achievement to crack the '08 and get this done, and UGR seems to be an amazing builder, doesn't it still make sense to start with the '06 (cheaper to acquire, cheaper to build (no vvt))? Just wondering.
It would depend on the route you took. An 03-06 platform with Striker heads and a nice Turbo cam will make similar numbers under the same conditions as a 2008 with the VVT set up similarly. Block wise, yes, they will likely end up with similar or identical bores and strokes once everything is set up, run similar rotating assemblies, etc. There are some tid-bits that are different in design such as hardware sizes, but when it comes to the aftermarket, either one can be brought to comparable specifications. The 03-06 use 1/2" hardware, while the 08+ is M12. 1/2" hardware nets a 20% strength increase over M12, so it is likely that some of the big builds would experience an issue if not increased in size. 1/2" hardware has never experienced a problem that I am aware of, especially after studding- but the 08-09 would require a jump to 9/16 or M14... a pretty large cost in machining, let alone custom hardware. 08-09 has a more stable valvetrain out of the box. Some people like DBW, some dont. The G3 Computers can be worked with. The G4, not yet, maybe not at all- requiring Motec support.
Basically, for an "all-out" build, the numbers will likely come back similarly. The 08-09 cars have some drivetrain advantages out of the box, The VVT cars will be "more refined" in the larger packages especially, but at a higher pricetag due to system controls and other machine work. Smaller packages will likely be astronomically more expensive on the 08-09 cars, as any type of FI requires a LARGE amount of engine & control system changes...
They both have their advantages and disadvantages at different break points...