it will help drastically but will not help as much to fight heatsoask as front mounting it in some way would. As an example, one of my old roomates had an impulse turbo awd. It has a top mounted I/C. The I/C had a rubber gasket to make a good seal to the opening in the hood for it. Some shop that worked on it lost the rubber seal. Immediately he started noticing a difference in the smoothness of the power.

it really makes a difference having a good flow across an intercooler. please, spend the extra $$$ and get that I/C front mounted. A greddy universal kit is extremely affordable. I can also recommend a shop in Sarasota that I feel would do good work affordably.