Hey guys. I just did a 3 inch X-pipe system on my Challenger with Spintech Sportsman Street 3000 mufflers. The car is Thunderous at idle, love it, and sounds incredible at WOT. The problem is at cruising speeds. I get a horrible drone from 1700-2500 rpm especially going up a slight grade. As I get higher in rpm, say 2700+ and 45mph+ it seems to quieten right down. I think the drone is comming from the front pipes in the system (between the headers and the X. Bad thumping type of drone and all I can think of is that it may be a scavenging effect causing the exhaust to echo inside the pipes. Any ideas on this?
3 inch system all the way back from my 500ish horsepower 451.
What are you guys running(or used to run) for X pipes?

Thanks.
Don.

I read in a book somewhere that 3" pipes are typically for 500" engines and above. I have a 505 spare and still plan on running 2 1/2" all the way.

My 71 has 446" with TTI headers and 3" with X pipe. No drone, I use Dynomax ST muffers.

My other car with a 340 with the same parts except with a H pipe sounds so much better. My

is the exhaust dumped infront of the axle or is it all the way back? that may make a diference

I have a TTI 3" system on my 360 from the stepped headers to the DynoMax Ultraflos ending at the rear end housing. Race only, but it sound good and ran better after the install than open headers. I did have to take the extra 60lbs out it added from elsewhere in the car and leaned out the jets a bit.

i have 3" x pipe pipes from my headers thru a pypes x pipe to aar style spintech mufflers. i just hear exhaust and these dump before the rear tire

I had Spintechs on a 2 1/2" system on a mild 440. The drone was unbearable between 1700rpm and 2300rpm. It really sucked for driving in town as that's the rpm range for 35 to 45 mph.
I suspect the drone vibrations came from the sides of the mufflers as the top and bottom are joined together by the welded forms inside the mufflers. I'm thinking of welding some angle iron to the sides of the mufflers to stiffen them up. Think it will work?
Also, decreasing the tailpipe diameter will lower the noise a little.

https://board.moparts.org/ubbthreads/show...rue#Post5975962

Check out this post. What I did completely eliminated the drone for only $13 and some labor.

I have a Challenger, 469 ci, 3" inch all the way out the back with a DR.Gas X- pipe and Dynomax Turbo if that matters. No drone. From what others indicate, perhaps it is those mufflers. However, it's hard to tell since no one has the exact same combination/setup as you.

Is it possible that your X-pipe is the issue. I'm no exhaust expert but maybe you are experiencing some problem due to the design or lack of due to the X-pipe. Supposedly they are not all created equally

One other thought and I'm not trying to be a wise azz, but are those mufflers designed to flow in one direction and are the installed properly?

Just a thought...

THe Dr. Gas X pipe worked great for me a few times.

I currently have an H pipe setup and it has awful drone. There are so many variables in any given car, it is hard to suggest anything.

Complete 3 inch TTI exhaust with X pipe on a 440, no drone here.

I'm running a 3" TTI system with x pipe and dynomax mufflers. No drone.

Well built 440 with 3" X and Dynomax Turbos. No drone but not quiet by any means. I had ultraflows on it and actually prefer them at cruising speeds. The turbos seems a touch mellower around town but much louder in the car at highway speeds then a straight through muffler.

Going back to the straight throw design, this time Borla Pro XS. A touch quieter with more performance.

I have a 78 Transam with stock manifolds an x pipe pypes 2 1/2 ex. and dynomax turbos that has bad drone. I have often heard that stock exhaust manifolds can give you drone easier than if you have headers. My Charger's drone was comletely eliminated by installing those 90 degree type pipe resonators. So I will probably be doing it next.

they sound HORRIBLE! dan

Don, those mufflers tend to resonate and it is tough to get enough of another muffler on to stop it all. Especially with a large powerful engine.
Like Flowmasters, not much is designed into them to stop or minimize resonation.
Tom

My sb 408 has a 2 1/2" x-pipe system from hooker comps, to an x, through $18 summit turbo mufflers, and a quick turn out in front of the wheels with 4"tips.

The car is a little rumpety loud and has bass at idle, and she's incredibly loud on decel. (4 spd) especially @ 4-5k rpm, but is actually pretty quiet at cruise. It is nice to be able to feel like I can drive kind of quiet.

Any time I'm in the city I am reminded the car is not quiet- the buildings really keep the sound in.

68 Fury, mild 440, Hedman shorty headers, 2 1/2" X-pipe, Thrush 19" turbo mufflers, 2 1/2" TTI tailpipes.

Had this exhaust on the car for a long time and had no objections. I

In trying to reduce some vapor lock issues, I blocked the heat crossover in the intake. Upon driving the car I now had a *terrible* resonance around 2000-ish RPM (just a guess, I have no tach). It happened at 'neighborhood' speeds and made the car so obnoxious it was practically undrivable - it had to be a 10-20 dB resonance.

I re-opened the manifold crossover and the noise was gone again.