Yeh, I considered twins, but the cost to have a custom set of 1 5/8" TT headers is too prohibitive
We took an existing set of B&Bs and modified them for twin turbo use. So they are not pure "one off" custom headers, and dont carry that price hit.
We cut them after the collectors, added a bit of pipe and the flanges for the turbos. The passenger side turbo needs to be re-clocked and some clearancing done on the motor mounts.
for some pics of the install.
Id up the C/R to 8.5 with EFI you have much better control over your AFR so you can take advantage of higher boost levels, other than that your build sheet looks fine.