Ive driven similarly set-up msp's with the Perrin fmic, TurboHoses smic, CustomMSP smic, and the HiBoost fmic (my own).
I will say that with the hiboost, because it is relatively small, there is no real lag. Our turbo is pretty small and spools up very quickly, so i agree with Knox that the change in volume isn't significant enough to give lag. boost rise IS a tiny bit slower than a smic, but hardly noticeable unless you obsess over it.
My experience with the smic's -- great product. Flowed well, really opened up the car, decent cooling i assume because the car pulled way harder. However, after a few runs it does get heat soaked and you lose a lot of power (as in it fealt close to stock). Yes this was in texas, yes it was hot, but regardless the thing sits in your engine bay so it's gonna get hot for everyone. fmic's are easily cooled by ambient air, smic's are not.
The Perrin absolutely does lag. It is a GREAT intercooler and does its job incredibly well but by shear size you can notice a definite lag. If you're looking for big boost, big numbers, larger turbo, etc. then this is absolutely the system for you, but im sure it could be frustrating for some in a daily driver.
ALSO -- BIG THING you have to account for that most people don't think of about fmic. YOU WILL WANT SOME SORT OF ENGINE MANAGEMENT. When you add a big-ass intercooler with a ton of piping, you change the engine's system A LOT. There's more volume, the turbo is working more, the air travels farther from the MAF to combustion, and it's cooler. The stock computer doesn't agree with things very well. My friends' car with the Perrin was almost un-drivable on the stock computer, but once tuned it was fine. My car wasn't quite as bad, but it was very frustrating due to bucking, bogging, great power/then none, initial lag when you punch the gas, etc. Some sort of engine management will save you a lot of frustration, not to mention give you more power. It basically just ties everything together so it works together for you. A smic won't require this, though it definitely helps
sorry for all that length, but those are my experiences. All those cars had cai, the mentioned IC, hardpipes, 3" exhaust, 8-9 psi. I have ran my car with the hiboost on stock cpu, stock unichip, and custom-tuned unichip. The Perrin i drove with stock ecu, then tuned MPI.