To save the SC2s for the track, and to be able to enjoy the car on the street, I switched to Continental Extreme Sport DW. Went with 295/35 in front, and 325/30s in back. I enjoy the combination and they are exactly what I wanted.
No bypass line. Not aware of the issue that you are asking about. But, there was never any suggestion of inserting a flow restriction in the system. That is a conversation you might wish to have with VMP.
I've been running this pump for a couple of years. When my OEM pump died, I installed this kit with an Afco cooler and Canton/Moroso tanks. The pump is a GT500 model, modified by VMP. Installed without issue, and has been working fine ever since.
Not to twist the thread too far... I am currently eyeing the Apex SMs. R model size, without being a copy. Affordable, and lighter than the OEM wheels.
Just be aware that just because you see a red badge, it doesn't mean that it is an R model. I see enough faux GT350s to be leery about what is really behind the lipstick.
These days - badges, stripes, wheels, and spoilers don't amount to much.
I used an AFCO unit and a VMP modified GT500 coolant pump. Install was simple. I used ramps, without removing the bumper cover. Cleaning and painting the bracket took the most time. No problems, no complaints.
Reading multiple threads, you may run into a couple of issues going to your local muffler shop. They may not stock SS pipe, and even if they do, it may not be the size required. Even with the kits available you should carefully compare size and material used.