Race Pro drone needs to go
 

So I finally got my 1967 GTO back on the road but the drone from the exhaust is terrible. I have a 2.5” Pypes system with race pro mufflers and X pipe. I’m running RA manifolds and the exhaust exits just behind the rear bumper. The mufflers sound great at idle and wide open, but at cruise, the drone is really bad. Bad enough it rattles the shifter and anything in the center consol.
What should I do!???
I am considering changing mufflers to something a little more mild. After some research on this forum, it seems there are a few running the dynomax super turbo muffler with good results. Ive read the 20” is super quiet, maybe too quiet for some but honestly that sounds pretty good to me. I see there are two types of dynomax mufflers people like, 14” and 20”.
So what do you guys think? It sucks to spend $140 in mufflers after buying a complete exhaust system..... Any other mufflers you guys would recommend?

I got rid of the drone on my 69 bird by replacing the X with a H pipe.FWIW,Tom

I had such a "drone" in 1983 with a Midas muffler system on my then 1970 YS 400 GTO.

I did not have that situation on a subsequently owned 1972 455HO GTO with Flowmasters.

Are you sure you are not “grounded” to the cross member or somewhere else? I can’t imagine sound wave intense enough from exhaust to make parts move. I’ve used the Race Pros in 3 of my cars with x pipes and not had the problem. Although I do believe the X pipes are the problem. An H pipe doesn’t seem to do this.

I’d tend to think this also.


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What mufflers? Where does the exhaust exit?
I would hate to cut up a brand new exhaust system to convert it to a H pipe just to find out I still have the drone....

I think the most logical thing to do is swap out my RP’s for 14” super turbos ($100) and if I still have the drone, fab up an H pipe to replace the X pipe

My exhaust is 2 1/2 all the way back to below the bumpers.I actually tried a couple diff before I changed the Xpipe.My muffler of choice is Hushpowers,I took them off and put on super turbos.Both had a drone at around 2000.I knew the Hushpowers did not drone when I had a H pipe.Went to a new shop,told him I wanted a H and he put in the X and acquired the drone.I finally pulled the X and put a H with the super turbos and it went away.To me the Hushpowers were a little louder at idle but the super turbos are louder thru the rpm range.When I get off my lazy butt the Hushpowers are going back on.Tom

My TA had a terrible drone with an H and flowmasters. An X and Ultraflows cured it.

Wow totally mixed results. I guess the bottom line is the majority of RP users have drone.
Well after driving the car to family’s houses today, I went ahead and ordered a pair of Dynomax 17749 mufflers. I can’t take the drone and I didnt build this car to be loud and annoying. I built it to enjoy. I will post up my results and hopefully some videos.

For the record, nowhere is the exhaust “grounded” or touching the frame.

yeah lots of mixed results & opinions on what "drone" really is... i have 3" race pros on a 2nd gen firebird with 3" pypes full exhaust out the back & an X... i would say very little if any real drone, there is a small spot at about 2000-2200 rpm that has somewhat of a resonating sound, but far from a bad drone or rattling the shifter or items in the console & my cruise rpm at ~65mph is closer to 2500 so it goes away real quick. this is on a 500+hp 467 stroker with alum e-heads & big 2" tube hooker super comp headers. cant imagine yours would be so bad with manifolds & 2.5" pipes.

i have another 2nd gen car with a mild cam 400 & H pipe & 2.5" flowmasters & its drone is much worse at a certain rpm but the exhaust is quieter overall so its hard to compare.

i had the super turbos on another car awhile ago with cheap muffler shop 2.5" pipes & no H or X with a mild cam 455 & it was quiet... almost too quiet. so im sure the super turbos will help but drone can be different on every car. plus if power is a concern, the turbos will rob some power compared to the straight through style race pros.

hope it works out for you.

As been said,there is usually some drone at some RPMs.My ordinary driving RPMs is at about 2000 so that is where I DONT want the drone,if it is a a RPM range I go through it is not a issue for me.Tom

Dynomax works for me. Quiet at idle but really opens up above 2500 RPM. Best of all, no drone.
BBC with headers, original factory exhaust exiting behind the rear wheels.

We run X's in most stuff here nowadays. The 20" case Dynomax cures any drone issue we've had. My son runs an "X" on his fox body with smaller 14" case dynomax ultraflows and there is no drone in that one either.

My chevelle with 3" "X" system and flowmasters has a pretty good drone and the 2,000 rpm range, and I'm confident a muffler change will cure it, if I ever get around to doing it.

I run the Pypes transverse style "X" system on 2 F-bodies here which only comes with the crossflow racepro muffler design and I find both systems work fine with no drone present. On one of them I even installed smaller 2" tail pipes for a stock appearance and that toned down the noise at all rpms significantly.

I had Racepro mufflers on a dual exhaust system I ran on a blazer with an "H" pipe and it droned right at 2,000 rpm where I cruised with it. Matter of fact it was just flat out loud everywhere and I got tired of that quickly. I swapped the mufflers over to Street Pros, and it was much quieter every place.

https://photos.app.goo.gl/uyvP9tqnbdTFhJse7

Here is mine down the highway . 3inch full exhaust ,Walker Ultraflows.

weird... pypes says the street pros are louder than the race pros.

Yea man, that sounds great! Quiet and smooth runnin down the road.

Here is a video of the race pros:
https://photos.app.goo.gl/bgMXMG7j2FsmQQym7

It’s hard to tell but this is where the Drone is worst

My dynomax mufflers showed up today and they sound great! I quickly installed them and started the car for a minute but it got too late to take avid. I will post up a video of the dynomax mufflers tomorrow. But they did sound pretty good 😎

Here is a quick driving video at about 40mph. Again, the drone is really bad here but hard to tell in the vid. This is with the pipes race pros.
https://photos.app.goo.gl/fu9fWHXvqKDGykKU8

Yep, and I've never found that to be the case with any car I've used them on. If you want a quieter Pypes muffer, go with the street pros.

every car must be different, some say racepros/ultraflo's have drone, some don't.

the one set of street pros ive heard were on a 2.5" pypes X system with small hedman headers & ~425hp, they were noticeably louder at idle & lower rpms than my race pros with 3" pypes X system & big hooker super comp headers. the street pros had that flowmaster chambered sound.