Wintermute

I'm considering installing an SLP Loudmouth into my 2006 GT, and noticed that the tubing is only 2.5" (3.0" at tip, but a chain is only as strong as its weakest link). At some point, I plan on putting some headers on, but likely won't go as far as a supercharger. My question is that would going with a fully 3.0" exhaust system be prefereble, or even noticable/helpful compared to a 2.5"?

Thanks