Suggestions Wanted For 408 Stroker Mufflers

I went from flowmaster 40s to Welded Ultraflows. 3" to the mufflers and 2.5" tailpipes. The ultraflows were quieter and .1 faster than the flowmasters. The car still picks up .1 and 1mph with exhaust cutouts. The cutouts made the same difference on my 360 that ran 11.20s as they do now with my 418 that has run 10.40s.

I just recently cut the tailpipes off so I can relocate my rear shocks but I haven't fired it up yet.