I put mine on the passenger side between the grill and the radiator support. It's a small one that I purchased at Advanced Auto Parts and it fits well. I installed a temp gauge on the outlet side (trans to cooler). I also installed a small fan controlled with a toggle switch that pulls air thru the cooler if needed, so far I've not needed it. Trans temp stays at or below 160-170F on the outlet side. I also installed an extra quart cast aluminum finned pan since the C4 doesn't hold allot of fluid and I use B&M Trick shift fluid. I run a pretty loose converter (3500). I should also mention that my battery is in the trunk but I think that there's still enough room for decent airflow even with the battery. I'll post some pictures.