Okay, I have spoken to a guy who deals with turbo mapping for touring cars and Sports cars including Le Mans.
I have know Jeff for many, many years his opinion I value. He said the volume increase theoretically will put some small delay but in practice and if you do detailed maths this is very, very small (A few milliseconds). In practice and theory forget it. Lag is about spooling up and intercooler volume is only marginally related. He did say that some stock intercoolers with additional boost will be increase the pressure drop and heat the air in the process, he also said that really good intercoolers are expensive..... like £20k and in test they show the results.
The installation position will have an effect. If you drop inlet temp you can add spark and that will improve throttle response and move you away from det.
He also said water/meth injection is extremely effective and £200 USA kits work embarrasingly well.....