So while my car was at Mine's last week in order to solve the overheating problem, I decided to go ahead and have the Mine's front pipes installed.
I had changed my normal standard exhaust for the Fujitsubo Super Legalis R (89.1mm main pipe, 117mm exhaust tail pipe) quite some time ago, around the time I got a boost controller which raised the boost on the standard BCNR33 turbines to 1.0:
I also changed the standard catalytic converter for an Apex'i sports cat, and the standard front pipes for Fujitsubo front pipes.
I had not considered, however, that the radius of the cat - on both ends, was 80mm. And now, with the new GT-SS turbos in place - these have outlets measuring 70mm. So, the Fujitsubo front pipe dimensions are 60.5, 60.5 and 70mm. So - we are missing 10mm on each end.
The Mine's front pipes, however, fit perfectly - 70mm at the turbo side, and 80mm on the cat side.
Mine's Front Pipe Pro:
I considered getting the titanium version because it's nice and light, but 1)it's also more expensive and 2) prone to cracking, according to Nakayama-san. So, got the regular SS version above.
The car now SOUNDS different - definitely less constricted, but also more baritone at full throttle. And, it seems that the engine response is a bit better than before. When I had picked up the car, Niikura-san had said that the front pipes were causing the car to sound a bit different. I now see what he meant.