Grimmspeed Top Mount Intercooler Kit Inc. Splitter For Subaru 15-21 WRXGRM 090070 Meticulous Engineering, Unparalleled Craftsmanship Replace that undersized, plastic stock intercooler with a GrimmSpeed Top Mount Intercooler Kit, featuring cast aluminum end tanks, large bar and plate core and TIG welded construction. The factory FA20dit TMIC is well suited for stock applications, but when boost levels are increased, the higher post turbo air temps contribute to pre detonation (or 'knock') and loss in power. The GrimmSpeed