On your 3V 2007, it goes on the DRIVER'S side. (all 05-10 cars). I use a JLT with my roush M90 on my 2010, but several other brands out there, like bob's autosports, etc.
http://shop.bobsautosports.com/Mustang-GT500-Oil-Separators_c20.htm
American muscle sells several brands.
http://www.americanmuscle.com/mustang-oil-separators-0509.html
What comes out of the catch can looks like a chocolate milkshake..with the can almost full every few months. (mixture of oil, unburnt fuel, condensation, etc). Once I switched to 100% synthetic engine oil, the amount collected in the catch can was reduced by a bunch, and looks like eng oil, not a choc shake.
At the same time I switched to 100% synthetic, I also started using FRPP oil filters. They are 50% heavier than oem, and contain 60% more filter media inside, and use high temp silicone rubber seals, handle high temps and high pressure.
Oem Ford oil is semi-synthetic..which is just 2-5% synthetic, and 95-98% dino oil..it's junk. I use 5W-30 since I have a blower. If NA, 5W-20 is just fine...but either way, use some real 100% synthetic, like mobil-1, etc.
Without a catch can, you will end up with oil all over the elbow of the blower, all over the rotor pack, Inter-cooler, and also collects one helluva mess inside the Roush aluminum intake manifold. It will also lower the octane rating of the gasoline a bit.
