Hello woody.
2 videos from Motortrend / Freiburger for you:
The Power of 2.5- vs. 3-Inch Exhaust:
https://youtu.be/_PVXvHkr-Vs
Exhaust Header Bash! Testing Power Loss From Dents:
https://youtu.be/azPKIjxmmdU
OK, the engines can't be compared directly, but the result will be similar.
Please also note that the 2.5 exhaust system is different to the later 2.7/3.2 exhaust system.
On the last photo it looks like your system has only one exhaust pipe at the end. If that is like it looks i would say that's a design fault. Not because of optical aspects, but of technical aspects (overall diameter).
Very interested to hear about your final results.
Regards, Markus