I would think them to be worth more than 8 or 12 hp. The stock manifolds on a "regular (as in "low performance")"440" are little more than "logs". Probably some "torque" to be had there as well. As usual, - YMMV. Regards, DaveG. ----- Original Message ----- From: <FltSgt@xxxxxxx> To: <mailing-list@xxxxxxxxxxxxxxxx> Sent: Tuesday, August 17, 2004 9:31 AM Subject: Re: IML: Magnum/TNT exh. manifolds > Rob > > When I called MoPar Performance to see what the difference was over my OEM > Imperial dual exhaust they stated the TNT etc manifolds are five to eight HP > more depending on your total system. As it turned out you cannot use the 67 and > newer drivers side ( A,B,C or whatever bodied ) manifold due to space design > on the 1959 to 1966 Imperials. But if you happen to have a '67 or newer > Imperial w/o the TNT and etc exhaust system, it will aide in the hill climbing > ability or Interstate mpg figures. > > Rodger & Gabby > Colo Spgs > > '47 De Soto Custom w/Fluid Drive & passenger door mounted swamp cooler > '63 Le Baron w/F-Sweep trunk lid & std A/C > '66 Le Baron w/dual A/C & reverbed AM/FM > '70 Overlander - InterNational > >