Thanks, TN. I've checked out the link, although I think I'll play 3. Bc4 and aim for the Evans gambit.
 
I was looking at 6. b4 because there doesn't seem to be an appealing way to approach the Max Lange. It seems like both 5. O-O Nxe4 in the two knights defense and 4...Bc5 5. O-O d6 6. c3 Bg4 result in white not having an edge or interesting unbalance in its favor.

Hello all, this is my first time posting.

What do you think of 
1.e4 e5 2.Nf3 Nc6 3.d4 exd4 4.Bc4 Bc5 5.O-O d6 6.b4?
Is this known to be dubious?

It looks like white has a fun game after 6...Bxb4 7.Bb2 Bc5, winning the pawn on d4 to go back to "only" one pawn deficit. 7...Bg4 8.Bxd4 Nxd4 9.Qxd4 looks great.

Perhaps 6...Bb6 7.Bb2 Bg4 8.c3 (transposes to 6.c3 Bg4 7.b4 Bb6 8.Bb2) Ne5 and then 9.Bb3 or 9.Na3 is unpleasant for white with doubled f pawns. Could white push the bishop away with h3 and g4?

Thanks.