[Chuck Moreland]

It is not easy to fit a cooler behind the stock valence. There is not adequate space.

Some do this by cutting into the trunk and mounting the cooler inside. Then create an air box to vent the air and seal the trunk. Others modify the valence, moving it forward. This doesn't really stock.

Another choice is a second cooler in the driver side fender. Run them in series.

You didn't say which mocal you have but in general the fender mount mocals are not the best choice. You would likely improve your cooling by using a carrera style cooler. This is about the biggest cooler you will get into the fender.

You could also use finned oil lines. This alone should be good for about 15 degrees.