Well done mate - good choice and glad you went for dual channel, did you go for side brackets as well?
Fitting it yourself or have a good friend to help? It's a daunting task if it's your first - just need to take it easy and work/rework everything before starting
Have you double checked no internal wiring where you are going through roof?
Professional sat installer told us how they were fitting system to brand new A/T and they ended up drilling where internal wiring loom was - didn't dare ask how they overcame problem as they were fitting system to our brand new A/T!! Would have been better if they had on ours as we only kept it for 11 months and it's still for sale where we traded it in - over 12 months later!!!?
Take care, best wishes all