4" is 2"x2"x3.14 = 12.56 sq. in.

6" is 3"x3"x3.14 = 28.26 sq. in.

The flare is not calculated as any more than the tube being its based on overall volume of the tube, the length will determine your tuning.

Hope this helps

Garett

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RD Audio Dealer
DD Dealer

Aaron's 97 Cavalier Trunk

1 Z1
1 9515
1 Not so good Optima Battery
4 runs total of 1/0

Certifiied:

152.0 Iasca
150.4 Db Drag