There is a number of options really.

As above, you could fit the large GRS intercooler.

There is also a guy on here who has fitted a cosworth 4x4 intercooler behind the grill with a custom made rad (probably looking a £400.00 all in. Can't remember his name "mind has gone blank")

Other people have fitted a cosworth 2wd intercooler again behind the grill and tilting the standard rad back to providethe extra space required, similar to what Karl does on his twin cos intercoolers.

The choice is yours.....