[RCLapCar]

Here's what I believe to be true based on the various things I read on here.

The V6 and V8 have identical frames. The differences between the suspensions are minor (sway bars, struts and some links in the rear I believe). If you upgrade the suspension then you would most likely replace all these parts anyway.

The V6 manual has the same rear diff as the V8's (only the auto has something different). And if you are going to put serious power into it an upgrade would be required anyway.

If you plan on replacing the entire drive train (engine, trans and diff) then the V6 is a great start. Again I do not claim to be an expert on any of this just what I read over the many hours spent here.