Lantana. I need to know how much power you plan making (max) redline of the motor and elevation where you live.

Yo have pressure drop across the intercooler because hot air takes up more volume. When it's cooled through the intercooler it becomes more dense (takes up less space) so it loses pressure.

Ar is a trade off. Smaller ar will spool sooner but it limits overall power potential. Larger ar will spool slower but has a higher power potential for the same turbo. Provided you aren't at the turbine or compressor wheel limits.

With rear mounts you loose thermal energy through the exhaust so it will spool slower anyways. You can ceramic coat and heat wrap the exhaust to make up for it.