when I installed mine I notice a slight increase in lag, nothing great, now I dont notice it. With a bigger intercooler you can run more boost and in hot weather run cooler intake temps, that was the main reason i got one as I lost upto 40kw in summer. With standard turbo its not recommended to boost above 12psi, other things I noticed was the aircon took longer to work but works fine and the engine temp rose by 2 deg. 82 to 84