Install an H pipe, it helps My last build, I changed my mufflers to 17222 Ultra Flows, I ELIMINATED my H pipe The drone, loudness, stereo sounding exhaust was a bit much, I reinstalled an H pipe, MUCH better
Thanks Mark. The H pipe solution is going to take some work on the Riv. I know placement matters and the only location is right in front of the trans or way back near the rear axle. I think that is why resonators were used originally. I'm dreading the muffler swap on the Riv. It is the easiest solution at the moment. The convertible is a breeze. The one muffler came out easily since the system is practically new.
I have a pair of Dynomax 17749 with and H pipe on both my 64 and 68 Skylarks Nailhead on 64 and 430 with headers on the 68. The Nailhead has drone about 1800 RPM, but I am very rarely ever in that range (manual shift). I am usually above 2000 at any steady cruise(in town/off highway), and 24-2800 highway. Pipes exit behind the bumper about 2-3 inches. I do not seem to have any drone at all on the 68. The pipes are dumpers just in front of and below the rear axle. It is very "throaty" at idle, so it may just be the "drone" range is lower than I ever drive steady. I like that they are not obnoxious loud, but nice in the 20 foot range. Hope that helps someone.
Can you add something like this near the tailpipe? Funny as it may sound a glass pack will reduce a ton of noise when there is a muffler in line. https://www.motorwise.ca/auto/d/flt...iC3Nep_QfPmHqNCavbvpmZrC2kjbT2iYaAmMFEALw_wcB
I did have true cherry bomb glass packs on the Riviera before the rebuild circa 200X. Weird how I completely forgot about them as a solution. I loved the cackle they made when letting off the gas. welp. I have the remaining 3 mufflers arriving soon anyway - returns not possible when in route. The more that I think about it the more I think I want the Cherrybombs back. Certainly less bulky on a goofy chassis like the riv. I may have to fight the pipes to line up straight. Weird how I completely forgot. But.... I hopefully can swap all 3 remaining mufflers in an afternoon - assuming all is well. I just may still with these walkers. ...still trying to figure out how I completely missed the cherry bombs as a solution...........................................................
I'm trying to come up with a super quiet exhaust combination. So far I have stock manifolds, TA down pipes and 2 1/2" exhaust. 17749 mufflers. I bought the H pipe kit but not sure if it will help or hurt. Thinking about adding extra mufflers or resonators at the back.
Just swapping one of the quiet flows on my convertible which does have an X-Pipe has turned out well. At this time I did not want to cut up the pipes to add stuff that should be taken care of with just a single good muffler. But I am not going for performance. As others have suggest, resonators (pass through pipes) could help reduce sound levels w/ little performance loss.
My little 2000 Chevy Tracker with a 5 speed and 2.0 was noisy with a flowmaster muffler and all I did was add a glass pack before the muffler and it made it so much more respectable.
Yes it does, BUT the general opinion is the real estate under the car will dictate where it goes. Mine is just behind the trans.
We used the Flowmaster 70 series. Big, but they flow good and they're reasonably quiet. In the past I have put a glasspack after a muffler, and that helped a lot too, but cost me about 0.15 in the 1/4 mile. If you can get an X-pipe those are best, but H-pipes are a decent 2nd choice if you can't put an X. -Bob C.
A company called "Vibrant" makes some high end quality exhaust components including resonators, mufflers and exhaust fab parts. ( even in titanium) A number of high end fabricators use their products. I just replaced my raspy flowmaster 40's with Vibrant 1127 3"street mufflers and like them a lot. IMHO better acoustics, engineering and manufacturing quality than most other exhaust companies
I have the stainless 2 1/2 inch MagnaFlow system on my GS455 with stock manifolds and an X pipe. It's mellow with only a very slight drone at about 2000 but not enough to be annoying.
I have also found that exhaust parts are one of those areas where you get what you pay for, so a few extra $$ might get you better results. -Bob C.
For the convertible did the muffler swap work... NOPE. !!!??? Both Quiet flows installed. Yes the exhaust is quieter, shockingly not really quieter than with one Pro Street and one Quiet Flow. Is the drone gone? No. Is it quieter yes. Is an annoying range still there yes, but quieter with a very unique sound. I think its the headers. It isn't like an exhaust leak but to be sure I am going through each U-Bolt. It is no sound I've heard before on a 455 with headers, or a convertible with stock exhaust. Its very odd and I am sure I will not be able to record it. Time to regroup and rethink. I don't have 350 stock manifolds that isn't an option. Plus the performance is still great, still tire chirping 1-2 but with a little less crispness as compared to when the Pro Street Mufflers were in.
