Hola If this was my Imperial and I wanted to make it an " sleeper ", I would first go to dual exhaust into a good " X " and then the mufflers. I would not accept any short muffler in the muffler's space due to the GTX sound they produce which is very non-Imperial. This system will give you better performance now and permit all other changes to happen in their best manner. The second item would to start looking for any 360 from 1975 and newer. The local pick & pull here charges $100 per engine ( long block ). Start making this junk yard builder 360 into a E58 Clone. If you go the 360 route also use the 360 exh manifolds since they flow better than the same looking 318 manifolds. The 360 over the 318 equals out to forty-two more cubes. This is a very hard item to over look. If number two of above is to much, just pull the 318 heads and have any local machine shop cut in a set of stock 1.88 360 valves for your Imperial. Use the same 360 E58 or like cam for the Imperials 318. Due to the torque the 360's have, MoPar only put the small block version of the 727 transmission with this engine. If you feel that you must change the gears in the rear axle take a hard look at the 2:94 gears over your current ratio. This ratio will keep your Imperial as an Imperial and do a lot better on the blvd vehicular debates. And again this is a easy pick & pull or ebay item. 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 ( Air Stream Trailer ) '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