Well now, this just ain't true. Quieter & better flow IS possible. Stephen usually orders the 3" unpacked versions because his customers like them the best. BUT, 95% of the 'Packs I build are with packing (noise absorbing) & no complaints. 2.5" are good to upper 400 HP range & they are quieter than the 3" ones. 3" ones are full-boogie high HP class, & not too loud either.
-Eric