I want to quiet down my exhaust..I need some help.

[Ms Grumpy]

I currently have the Flowmaster American Thunder system on my car. I want to quiet it down so I need to know what you guys think would help, because the Flowmaster 40's are just too loud. Don't get me wrong, I like the rumble, but I plan on driving this and it is just too loud for distance driving. I just don't want the droning.

Dart 400 Short block assembly
Dart 11221111P 72 cc heads with 180 runners
Comp 987-16 1.430 springs
Comp cams hyd roller 294/300 .242/.248 .540/ .562 110 deg lobe.
Comp roller ultra pro magnum roller rockers 1.52
Pro magnum push rods
Dart sportsman II dual plane intake
Holley 770 street avenger
Hooker comp headers 2451 full length
Flowmater 2 1/2 American thunder exhaust and series 40 mufflers
MSD HEI
MSD 6AL2
3.73 gear
3200 stall