I'm going to eventually get a shot at an Evo 10, so I'll let you know on that one
The Evo 10 has a twin scroll turbo, so it shouldn't suffer from noticeable lag...AFAIK it's to do with the factory ecu settings...
One thing I know for a fact being a member on the U.S based Evo 10 forum is that tuning one, even the mildest of tunes transforms them into a completely different animal !!!
Just derestricting the exhaust alone releases up to over 40kw of additional power...and tuning the ecu produces huge power increases and large reductions in fuel usage, as they are running very rich (stoich ratio) from factory...same applies for the Ralliart in terms of stoich ratio...
With the Ralliart I drove, I cannot complain about lag at all, it was not as responsive or torquey as an MPS3 down low, but seemed to very quickly generate speed and cover ground anyway, it definitely seemed to get to 100km/h faster, that SST trans helped alot and along with the fact that the MPS3 is starved of at least 20% of its torque output in 1st and 2nd gears dosn't help it in the run to 100km/h...
If the MPS3 had access to 100% torque output in 1st and 2nd, it would definitely be capable of low or even sub 6's to 100km/h even with the basic manual trans as it only needs a single swap to 2nd, no need to go into 3rd gear to hit 100km/h...