dbaker9323 Posted January 31, 2016 Share Posted January 31, 2016 Hello. I am the proud new owner of a very original/pristine 1966 Riviera: Aquamist, matching deluxe bucket seat interior. Purchased from a fellow ROA owner who took meticulous care of it. My question is this. It is equipped with glasspack mufflers, which are a bit loud for my taste. On my 1971 Riviera GS, I have a Magnaflow system - while it has a nice rumble, it is much more subdued. I am contemplating putting Magnaflow on the 1966 - should I expect the 425 engine to with Magnaflow exhaust to sound the same (or very similar) to the 455 engine with Magniflow? Or does anyone have different suggestions for nice sounding (but not too loud) mufflers? I don't want to go back to the factory stock set up which would have no rumble. THANKS David BakerROA14362 Link to comment Share on other sites More sharing options...
RivNut Posted January 31, 2016 Share Posted January 31, 2016 Most of what you hear will depend on the size of the pipes in and out of the muffler and the distance the muffler is from the manifold. Are you going to keep or eliminate the resonators? Or perhaps some previous owner has already eliminated them. To answer you original question, I don't know. 1 Link to comment Share on other sites More sharing options...
smithbrother Posted January 31, 2016 Share Posted January 31, 2016 Ask the muffler company. Dale in Indy Link to comment Share on other sites More sharing options...
Pat Curran Posted February 1, 2016 Share Posted February 1, 2016 I took the resonators off the stock exhaust on my 69 and it gave me the mellow rumble that I was looking for without being too loud. 1 Link to comment Share on other sites More sharing options...
petelempert Posted February 1, 2016 Share Posted February 1, 2016 Another option might be to add a smaller set of glasspacks resonators to the back end. It will pull down the overall sound and also eliminate any popping and barking when you decelerate. On my 63, I wanted more sound than the factory muffler over the axle, but its a challenge to hang dual bigger oval mufflers on that model. My muffler shop put glass packs up front and to small resonators tucked under the rear quarter panels. You can't see any exhaust hanging down from any angle and the sound is mellow with some burble. When you really stomp on it, the sound is amazing. PRL 1 Link to comment Share on other sites More sharing options...
bb1970 Posted February 1, 2016 Share Posted February 1, 2016 (edited) Here's my exhaust. Hard to tell in 22 seconds. Big improvement over the glass packs I had. It's a Magnaflow cross flow muffler 2 1/4" pipe. Turned down by the bumper. Edited January 15, 2017 by bb1970 (see edit history) 1 Link to comment Share on other sites More sharing options...
64Rivvy Posted February 1, 2016 Share Posted February 1, 2016 I would definitely replace the glasspacks since you already know you don't really care for the sound. They will also only get louder and louder over time. I would go with one of the quieter magnaflow muffler sets and ask the muffler shop to mount them where they think drone would be minimized the most. I recently switched out a set of magnaflows on my 69 Camaro to a set of Stainless Works mufflers I got from SpeedTech. They have a nice low rumble at idle, scream when you hit the gas hard, but are relatively mellow at cruising speeds and normal driving. The Magnaflows on there were so loud and the drone was killing me, but I know they were the loudest magnaflows you can get so that was part of the problem. The sound should be pretty similar between the 455 and 425 but much of it has to do with the cam in each each engine, particularly the sound it will make when idling and at lower speeds. Let us know what you end up doing. Raul 1 Link to comment Share on other sites More sharing options...
dbaker9323 Posted February 2, 2016 Author Share Posted February 2, 2016 Hey, thanks to all for replying! Good suggestions all. Link to comment Share on other sites More sharing options...
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