Hola As we all have witnessed from the writings MoPar started making exhaust manifolds to help out the flow of the big V8's. After the issue of the 1967 to 1978 Imperial some lucky owners had their prestige car with the 440 that had a boosted horse power. Since that time some owners have tried to copy the factories know-how by installing the coveted HP / Magnum / TNT / etc exhaust manifolds on their ride. But, the 1959 to 1966 Imperial owner who wanted to raise their 340 horse powered 413 or 350 horse powered 440 could only go for the dual exhaust. The old style duals would add 15 horse power at the most over the single exhaust ( Maybe this was a factor in having the sporty "rag-tops". ) Due to frame design and the location of the engine on the 1959 to 1966 Imperials the better HP manifolds will not fit the drivers side due to design space. This is the old story said over and over about the drivers side needs a center dump manifold. I do believe MoPar made it possible without sending a letter to all the 1959 to 1966 owners. The late model Imperial ( 1972 - 1978 ) passenger side exhaust manifold with the casting stamp of 3830820 ( http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&category=33632&item=7958442195&rd=1&ssPageName=WDVW ) and the late model drivers side center dump manifold from a truck ( http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&rd=1&item=7958691984&category=33632&sspag ename=WDVW ) both have the same design appearance. Some could say they are the latest of exhaust technology of the early 413 / 440 design. Now that I'm showing ya what I am thinking, do any of you have any data to support my thoughts in aiding the early power readings with the newer manifolds ??? Rodger & Gabby Colo Spgs '47 De Soto Custom w/Fluid Drive & passenger door mounted swamp cooler '62 Crown Coupe w/std A/C & Auto-Pilot '66 Le Baron w/dual A/C & reverbed AM/FM '70 Overlander - InterNational Dbl '77 D150 w/360, NP 4 Spd, 12 Bolt Axle, OEM Buckets & etc ----------------- http://www.imperialclub.com ----------------- This message was sent to you by the Imperial Mailing List. Please reply to mailing-list@xxxxxxxxxxxxxxxx and your response will be shared with everyone. Private messages (and attachments) for the Administrators should be sent to webmaster@xxxxxxxxxxxxxxxx To UN-SUBSCRIBE, go to http://imperialclub.com/unsubscribe.htm