Increasing the intercooler surface area beyond that of the factory unit is all well and good but only if all of the ambient air is available to all of the upgrade intercooler so maximum heat exchange can take place.
The answer here is of course a revised under bonnet duct.
The new Process West 04-09 Liberty GT/Legacy intercooler addresses all of the above issues and it does it very well. Our new top mounted intercooler is virtually a small front mounted intercooler mounted in the engine bay.
With a massive 400mm flow length (almost double the factory unit) and a not too thick 90mm bar and plate core an effective top mount is now here.