They can be greatly strengthened. Lentech is putting AODs behind eight second Outlaw cars with more than 1100HP and even make a Pro5.0 version that can handle more than 1400HP. I'm running their Pure Street Terminator Lockup AOD behind my N/A 306 that's probably making between 425 & 450HP at the crank. Its all in the power flow and how the internals are strengthened. Its more costly than an AAMCO rebuild, but its worth it.
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Jeff Chambers
Trophy Stock #3
11.611 Seconds / 116.7 MPH
Chambers Racing Team