Michael Posted March 1 Share Posted March 1 For the folks running lower-rpm, higher displacement naturally aspirated engines (say, 400 cubic inch and above), what have been your strategy to get reasonably quiet exhaust that isn't too restrictive? I stumbled across Flowmaster's purportedly quietest series of mufflers: https://www.flowmastermufflers.com/products/exhaust/mufflers/street_chambered_mufflers/50_series_big_block/ . These would, coincidently, go behind a big block (Chevy). Muffler size isn't an issue, since my fuel tank is removed (S30) and there's a fuel cell in the hatchback area. My question is about simultaneously quieting the exhaust and keeping backpressure to a minimum. This would be dual exhaust, of course, with a conventional crossover pipe, and headers (for the moment, block huggers). Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted March 3 Share Posted March 3 Unless you are running high compression, I'd look elsewhere. These chambered mufflers rely on pressure waves to cancel sound. Lower compression = less sound cancellation. I had a Flowmaster put on my '83ZXT against my wishes by the local Z shop back in '95 when I had to replace my turbo with a bigger one and had a 3" mandrel bent system with cat put in - because the owner had one in his DYNOED 600 HP 280ZX. I drove it home to try it not expecting much and it DRONED at set speed and was loud. I was back the next day and had them put in a DynoMax Ultra Flo center in/out oval canister muffler. Not only was it a bit quieter, it didn't drone and the car even spooled up quicker. The owner humbly said he'd learned something from a computer nerd. Quote Link to comment Share on other sites More sharing options...
Michael Posted March 8 Author Share Posted March 8 On 3/3/2026 at 5:23 AM, Brad-ManQ45 said: ... I was back the next day and had them put in a DynoMax Ultra Flo center in/out oval canister muffler. Low-ish compression, but very high displacement in my case. Current 461 cubic inches. Might eventually get one of those 598" short blocks and move my existing parts over. Would you recommend something like this: https://www.dynomax.com/mufflers/super-turbo-mufflers/super-turbo-offset-centered.html ? Maybe the 17769 model (3" in/out, largest in that series... I'd use two, of course). Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted March 8 Share Posted March 8 That would be a good choice if you can't go center inlet/outlet. Displacement doesn't translate to sharper pulses like compression does... Quote Link to comment Share on other sites More sharing options...
socorob Posted April 17 Share Posted April 17 I put a 3" in and out hushpower on my LS Z thinking it would be quiet. Its the only thing I dont like about the car, its loud and very droney on the hwy. Im trying to find what would be the quietest muffler that will fit in the stock location, I dont care if it takes a slight performance hit at this point to make the car more enjoyable. Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted April 17 Share Posted April 17 This is what I put on mine.... https://www.dynomax.com/mufflers/ultra-flo-welded-mufflers/ultra-flotm-welded-centered-centered-598.html Quote Link to comment Share on other sites More sharing options...
Michael Posted April 18 Author Share Posted April 18 9 hours ago, Brad-ManQ45 said: This is what I put on mine.... https://www.dynomax.com/mufflers/ultra-flo-welded-mufflers/ultra-flotm-welded-centered-centered-598.html Interesting. How quiet (at least subjectively speaking) are these? I am looking for a mellow, unobtrusive sound... actually I don't much care what it sounds like, so long as it is quiet, doesn't disturb anyone, doesn't draw attention, and approximates (more or less) a 1990s V8 taxicab, like a Caprice or a Crown Vic. In my application, space is not a premium, so huge mufflers (or even two in series, for each pipe --> 4 total) are OK... if that actually helps. Quote Link to comment Share on other sites More sharing options...
Brad-ManQ45 Posted April 19 Share Posted April 19 It's quiet compared to Flowmasters. You can converse well around town and on the highway. Quote Link to comment Share on other sites More sharing options...
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