Exhaust Pipe Size?
Thread Starter
Teching In
Joined: Dec 2017
Posts: 44
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From: Myrtle Beach S.C.
Exhaust Pipe Size? I have a Gen3 575 HP LQ9 with dual exhaust. It has long tube headers with 3" pipe. What size Muffler and tail pipes should i go with 3" or 2.5" ? I am not concerned with squeezing every ounce of Horsepower out if it, more concerned about drone and noise levels at Cruise/Hwy speeds. Transmission is automatic with overdrive and 3.70 rear end gearing. What size pipe 3" or 2.5" and any recommendations for Mufflers would be appreciated.
Thanks,
Keith R
Thanks,
Keith R
TECH Regular
Joined: Nov 2018
Posts: 467
Likes: 116
Resonators are how you get rid of drone if you have drone. Depending on the length of pipe you have run, you might need them before and after the mufflers. It's the length of the pipe that allows the resonance to build up, the longer the length the deeper the rumble because the frequency of the exhaust note is changed by the pipe length just like a brass band instrument.
But I would just go with dual 3" if it fits. There really isn't a great reason I can think of to go with 2.5" over 3". The mufflers and pipe are all going to cost close to the same.
For mufflers, go with actual chambered mufflers like a Dynomax Super Turbo muffler with the inlet/outlet both off center if you want a no-drone, closer to factory sound level. Any muffler that is a straight through perforated core with glass packing is going to drone real bad.
Get a couple 3" resonators as well. Placing them after the header collectors and also after the muffler on the tail pipe will kill any drone. Any length of pipe that is about 4' and longer is going to start making a drone. This is why you see newer cars with a muffler and like 2-4 resonators in addition to the cats. That's how many it takes to get all that resonance and vibration out...
I have nothing but glass pack welded to another glass pack welded to a muffler for basically the entire length of my system lol. It took a lot to tame the drone with a 4" pipe under a truck.
But I would just go with dual 3" if it fits. There really isn't a great reason I can think of to go with 2.5" over 3". The mufflers and pipe are all going to cost close to the same.
For mufflers, go with actual chambered mufflers like a Dynomax Super Turbo muffler with the inlet/outlet both off center if you want a no-drone, closer to factory sound level. Any muffler that is a straight through perforated core with glass packing is going to drone real bad.
Get a couple 3" resonators as well. Placing them after the header collectors and also after the muffler on the tail pipe will kill any drone. Any length of pipe that is about 4' and longer is going to start making a drone. This is why you see newer cars with a muffler and like 2-4 resonators in addition to the cats. That's how many it takes to get all that resonance and vibration out...
I have nothing but glass pack welded to another glass pack welded to a muffler for basically the entire length of my system lol. It took a lot to tame the drone with a 4" pipe under a truck.
Staging Lane
Joined: May 2021
Posts: 54
Likes: 7
Some good advice. Highly recommend one/some resonators along the way as well.
One point/option, only a straight-through muffler will not rob some hp...consider magnaflow as they are generally the quietest straight through muffler, the bigger the better for tameness.
One point/option, only a straight-through muffler will not rob some hp...consider magnaflow as they are generally the quietest straight through muffler, the bigger the better for tameness.
Joined: Nov 2003
Posts: 6,216
Likes: 236
From: Wichita KS / Rancho San Diego
The question is, what kind of car do you have and what can you fit underneath? Obviously a long case muffler is going to do a better job of suppressing drone than a short one.
Another fan of the Borla pro-xs mufflers. In my experience I find the opposite of what was mentioned above, straight through mufflers with a core do not drone and chambered stuff does. Ymmv
