This brings up a hypothetical that I've been pondering. Let's say a skilled builder such as Allan builds a street legal SLC with either an LS7 or LS9 crate motor, and gets it sorted out. You then take the car to a roadrace track with long straight(s) like Road America, where the speed advantage of a GT comes into play, as opposed to a Caterham or Atom. A skilled racing driver turns his best time in the car.
My question: What is the LEAST EXPENSIVE road legal production car that would be able to equal or exceed the SLC's on-track performance?
Here are the rules:
1. Same type of tires on both cars. Not necessarily the exact same size, but same model--Pilot Sport, Hoosier R, etc.
2. Production car must be a similar streetable GT that will comfortably seat two adults i.e. McLaren, Ferrari, Porsche, Pagani, Mosler, Koenigsegg, etc., no Caparo T1 or the like.
3. SLC is set up to be driven on the street--no race splitter, 1" ground clearance, or other things that would make it less street-friendly than its competitors.
4. No megabuck one-off motor in the SLC. LS crate motor with a warranty.
5. Same driver (a good one).
Thoughts?
Edited to add: My best guess for least expensive production competitor would be McLaren 650S.
JR
First, congrats to Allan. I've seen firsthand the kind of attention his car attracts in the wild. I can just imagine the McLaren driver's look after talking to Allan...
As to John's query, my guess is that there aren't many production cars that could keep up with a well setup SLC with a big engine.
If you take the 01 car's times from 2011, it runs faster than any production car I've ever seen. Why that car at that place in time? Because it was (1) well driven, (2) similarly powered as to your hypothetical, though possibly a bit under powered compared to a hot LS9,, (3) had about the same aero as a stock SLC at the time and (4) actually weighed much more than the specified SLC in your query.
So looking at the lap times for that car at that time, what is faster? We raced and beat Ferrari Challenge cars, race-prepped Vipers, Corvettes of all flavors, several ex-IMSA 911s (one well-driven example with over 700 HP), and many others. But these were race prepped, and not really a stock production car by any means.
That leaves the DSR and CSRs, but we are excluding the sports racers (as they are one-seaters, and not a production car by any means).
The next faster cars are the ALMS-spec GT cars. These cars are several seconds a lap faster than the 2011 championship-winning SLC, but they really aren't the production car you were looking for either, as they are to a stock production car as NASCAR cars are to stock production cars.
So what is there out there that can really compete?
The problem is that we really don't have comparable times for a McLaren, or an SLS AMG, or any of the other cars you mention. I don't think any of them have run at Summit Point or at VIR or Mid O. There was one Lamborghini that I think ran at one of the UTCCs, but was slower than the SLC ran there in 2011, with street tires, a very mild motor (for economy) and several hundred pounds of extra weight that a real street car wouldn't have. A comparable SLC would no doubt clobber it on the track.
I imagine that you'd have to get to McLaren P1 territory, or the Porsche 918 range before the SLC would start losing.
But that's pretty rarefied air, and I doubt that most of us will ever even see one of those cars up close and in person.
I don't think it's too much to think that an owner with a well-built SLC with a big engine and the skills to drive it is unlikely to meet up with a car that is actual competition on a road course.
But that's just a guess. Until we get a matchup with a good driver running both of them on the same road course at the same time, we'll probably never know for sure.
I'm sure Ryan would make himself available under the right circumstances to help set the record straight, though.
but clearly, I have misjudged the SLC's track prowess. 
