before you buy any unit talk to people about what they are using, as stated here that the Gen II is so yesterday it is the best blowing unit I have found to date and we have been installing them for years. I have them in almost all the cars we build and have not been disapointed yet. The new unit will be good as well but I do not see it blowing the volume that the Gen II will do as it will be smaller. My 69 Camaro is on the ground with all kinds of mods and the Gen II fits in the dash perfect you can hardly see the bottom of the unit. As for the Firewall all the bulk heads that they have will work. I would also look at the Dakota Digital controls for the unit to see if one of them might work we use them as well and they are very cool upgrades. I have some installed that I can send you some pictures of or post them up here for you to see. I hope this will help with some of these questions.