The race cover is 5.5". If you get the right boot, you can leave the valve covers alone like Matt said. The OBS looks tighter past the brake master cylinder than the Super Duty. I was able to get the 5" intake between the intercooler pipe and the master cylinder, but it is very tight.
Good Luck!
You'll love that turbo. I do and I'm only running Stage II injectors.
For me it's a little laggy when cruising on the freeway and I step into it, but as soon as it gets to about 7 psi of boost, it launches to almost 40 psi of boost very quickly. My 35 psi boost gauge it's enjoying that very much.....
. Glad Matt talked me into the ARP's.
Oh course I have 3.73 gears and 37" tires, so I'm only turning like 1600 RPM at 75 mph. Barely off idle!