MRC, wouldn't go anywhere near Litchfield.
There's been a few cases now where Litchfield cars have had to be corrected by MRC, there are various posts about it on their facebook posts (although they don't name the tuner, they just state competitor in their posts)
There was an interesting one of an RS6 owner who had a Stage 2 car and Litchfield had posted a picture of the car on their dyno, about a month later, the owner was complaining of continual misfire issues that Litchfield could not resolve, the same car (distinctive) was then pictured on MRC's dyno and the misfire issues were resolved. The comparison between the 2 maps was comical, MRC managed to find an extra 50ps or something ridiculous like that from the car. Customer posted saying the performance difference was night and day and that he had suffered no further misfire issues . Over on the RS246 forums, there have been a handful of owners who have went from Litchfield to MRC with issues.
Litchfield pay for all the press releases, Evo, Pistonheads etc so they do get a lot of coverage but if you dig deeper they are a pretty poor option in my opinion
I cant remember the exact figures posted, but if you do a search all will become clear, peak figures of 510hp or so with an intercooler but yet they started with about 445hp so the delta wasn't great. Don't be fooled by peak figures, take a start figure and an end figure and compare the inbetween.
445hp-510hp =65hp, so is just the same as a 400bhp car going to 465bhp. Dyno lottery, the 510hp car will behave the same as the 465hp car.
MRC as part of their cost give you a before and after so you can see the delta gains. Typically starting at 395-400 and tuning to over 500 so the delta gain inbetween is 100+ (On a Stage 2)
MRC/Revo/APR/Custom Code and pretty much every Audi tuner all follow the same Stage tuning logic,
Stage 1 = Software only
Stage 2 = Software and bolt ons (A must being a downpipe) Intercooler, Intake,
Stage 3 = Hybrid turbo and full bolt ons
Stage 4 = Big turbo and full bolt ons
Sometimes you get a Stage 2+ if extra fuelling requirements are needed.
Litchfield, well they have chosen their own Stage path.
Stage 1 = Software
Stage 2 = Intercooler
Stage 3 = Downpipe + Exhaust
Don't think I've ever seen a Stage 4 Litchfield Audi. If going by their GTR logic, hybrid turbos and above are Stage 5 +
Would you take your GTR to MRC or APR? Would you go for a big Nissan engine build with MRC? The same logic applies, why would you take your Audi RS to Litchfield when the expertise with the engines and ECU's lies elsewhere? Just look what's happening with APR at the moment, they have their boffins developing their Stage 1 file and its still not ready. MRC as we speak are developing their map for map switching ability, rumoured to be ready by this summer as they test it. Litchfield had their map out pretty much straight away.
There's a lot more I can go into, off the shelf, load and off you go vs time and effort, tweaking, logging, dyno etc
Litchfield are top GTR tuners no doubts, but in the Audi RS game, nope, not for me.
Edit, Litchfield did offer a very good package initially which included a tune and a fitted Forge intercooler for £1450 (ish). This lasted a couple of weeks and the price then increased to £2,100 so they lost their USP.
Also, MRC, APR, Custom Code (Iroz) all state that they will not tune the engine without tuning the gearbox so an ECU and TCU tune is required by the Audi specialist tuners. No such requirement from Litchfield.