Hrrmm, I've always felt it increases throttle response, not so much "lag" I don't know anyone who's felt a bigger core / pipes increase the RPM point where the turbo goes positive pressure. Maybe my naive understanding of "lag"
You'd think even a stock'ish GTR ingesting 400hp worth of air is going to fill that slightly bigger core pretty quickly, but alas it does affect throttle response. Ie, when your past the positive pressure RPM point, (say 4500rpm) and you get off / on / off the throttle. A good mate with an 430hp EJ20T noticed a fair wack of increased throttle response when going from stock top mount Air -> Water IC to a Plasma-Man front mount, and another 380hp EJ mate when replacing the stock Air -> Air top mount with 4" thick item. In these specific examples (back to back, nothing else changed) response, not compressor lag was effected.
Not any proper comprehensive ones that I've seen around. Fast acting pressure and temp senders before and after IC. Ambient temp, wheel speed senders and TPS logged by a decent logging box would be a damm good start. But who's going to find the time and effort to do that....? [Jaded Warning] LoL rem magazines and shiny alloy are the prime decider's for most ppls mods, not fact and data.