Hey, I like how you did it clean, but you probably should know that the hole you chose is for the alignment pins when installing the subframe. I bet they only use them for initial alignment during assembly of the car...but hey I thought I'd point that at.

Also, I think running the line down the drivers side into the trunk minimizes the amount of underbody exposure and of course running it near something protected is good.
I ended up running twin half size Gell cells in the trunk of my SVT and hiding them behind the trunk liner behind each wheel well. THe main line came in the trunk on the left then both batteries were separately grounded and wired in parallel.
I never got around to it but a good 100amp circuit breaker right in the trunk and one at the front by the strut tower is recommended in case of any shorts.

Former owner of '99 CSVT - Silver #222/2760 356/334 wHP/TQ at 10psi on pump gas! See My Mods '05 Volvo S40 Turbo 5 AWD with 6spd, Passion Red '06 Mazda5 Touring, 5spd,MTX, Black