John H kinda made my point...
It's not just about which is faster, and which has the higher dyno #. I think Doug Levin would dissuade anyone who just drives on the street and wants a "more powerful car" from going with his biggest kit (which makes, what, over 1,000lb-ft to the wheels?). It's got a LOT to do with WHO is doing the work for you.
Alot of people will say the prices are too high (and I don't think ANYONE could convince me that $65k is a reasonable price for a turbo job), but I would certainly pay more and go with a reputable shop than get a cheap job that blows my engine.
There are a lot of local guys who go with LPE. I've owned an LPE job, and driven a bunch, and you just can't beat their quality of work. My friend's LPE TT Z06 is devilish. It's so quiet and smooth and idles and drives better than a stocker, but when he gets on it, he roars past my GTS like I was standing still, and it sounds like I'm standing on the deck of an aircraft carrier listening to F-14's take off. Amazing.
I've never driven a DLM car, but I did do a lot of research, and in terms of supercharging for Vipers, DLM is the equal of John Lingenfelter.
The real issue as I see it, is not how to physically mount the turbos or how to route the lines - that's pretty much just a trial and error thing. And it's not what turbos to use, or how to plumb them - that's a research and trial and error thing. The real problem is making the car run correctly with fuel, spark, and compression (as in not too much). This is where folks like DLM and LPE excel. When my friend went to pick up his TT Z06, there were SEVERAL cars that had the "biggest" package another 'famous' tuner sells on them. They were all there being fixed by Lingenfelter as favors to the owners, who were past and future LPE customers. The work had not been done to make these cars run right, and they idled like crap, and drove even worse.
I'd rather have a QUALITY job that made 700RWHP than a hack job that made 900RWHP. You definitley want to talk to other customers who own these cars and get their feedback - probably offline since most people don't want to spout negative comments publicly. I wouldn't want to be in the first 5 to get a package unless it was someone who had a history of doing quality work, and attending to customers needs. At this power level, SOMETHING will break sometime, and that's when the name you picked becomes VERY important, IMO.
Sorry to be so long winded - I've "been there done that" in terms of working with tuners, and I've had good and bad experiences, and from now on, I'd only go with someone with an impeccable reputation for quality and support.