Thanks for the support, guys!
Here's the progress of the last few days:
-Reimported the lower part of the blower from the Vigero, as dukes2's blower has a lot of texture bugs
-Resized the upper part of the blower so it looks more like the Interceptor's blower
-Made collision to fit the blower
-Remapped the cuts on the front fenders so the texture looks better
-Readded Windscreen, as the Interceptor has it (oops)
-Closed the Gaps in the rear bumper from the old exhaust system (and UV mapped it as well as i could)
-Cut away the part in between the rear seats, rear window and the boot to open space for the stuff in the back
-Removed boot (duh)
-did some basic modelling and UV mapping on the interior rear to fill the hole.
-Added Barrel and Spare wheel to the back.
-The Windscreen does not break.
-The Spare Wheel gets Dirty like the normal wheels (it was expected, but looks weird)
-The Barrel doesn't get Dirty (again, expected, but looks weird)
PS: I extracted the Barrel and the wheel from the game files, so the car looks more "lore friendly", Instead of using the tanks from the real interceptor. Remember, I want it to fit the GTA world as much as possible.
I'd appreciate some help about the windscreen and dirt problems
I hope you like it!