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I've ran the true duel speed engineering set up for well over 9months now. Car sounded great when it was basically stock w/ headers no cats. I've since then done stag 2 heads, 228/228 cam and recently installed a DSC-1 pro charger. The car is mean sound aggressive and at wide open throttle it kills. To warm the car up I let run a bit but it pretty much wakes up the whole neighborhood. Not to mention the drone is ridiculous. The true duel system is perfect for a basic stock set up but now I'm looking to tone it down a bit To where I can have more drivability or even a convo inside the car.
Will adding cats and replacing the shitty bullet mufflers help enough? Or do I need to just go back to a catted y-pipe full exhaust set-up? I know I'll lose a little power either way but to me it's worth it if it tones down the sound/ drone in the lower RPMs. On the freeway the drone is reasonable but in traffic the car scares everyone I pass.
Does anyone here have a similar setup or situation they have solved before I dump more cash into unnecessary changes that won't make a bit of difference?
my advice, the farther away from the engine, the less difference it will make in power.
cats will definitely decrease noise. depending on flow rate, it may or may not effect power.
the type of muffler will affect the tone differently. chambered favors lower tones. straight-through fiber-glass packed mufflers tend to be quieter at idle and raspy as the rpm's go up. imho magnaflow mufflers tend to be the quietest.
if you want absolute quiet, you'll probably want to stick with an OEM-type, which heavily relies on chambers, diffusion, and reflection. i doubt you want that kind of restriction, however.
If your exhaust is dumped after the axle then it will always drone. Hopefully yours goes all ghe way out the back. Rasp should not be a problem with dual exhaust. Anyways assuming your exhaust goes all the way out the back, I'd start with good Borla straight-through mufflers. I like the XR1s, but Borla makes plenty of low drone mufflers. Otherwise Magnaflow also makes very good straight-through styles as well. If your system is still too loud for your taste, then Id consider adding cats.
FWIW - at the PRI show in Indy, Kook's claimed their green cats are restriction free to about 900 rwhp. They also stated since their cats retain heat very well and will enhance flow slightly to point that one customer gained 2hp after installing their green cats. They have another customer pushing 1200 rwhp through their green cars for over a year without issue. They are rated for 800 hp.
my advice, the farther away from the engine, the less difference it will make in power.
cats will definitely decrease noise. depending on flow rate, it may or may not effect power.
the type of muffler will affect the tone differently. chambered favors lower tones. straight-through fiber-glass packed mufflers tend to be quieter at idle and raspy as the rpm's go up. imho magnaflow mufflers tend to be the quietest.
if you want absolute quiet, you'll probably want to stick with an OEM-type, which heavily relies on chambers, diffusion, and reflection. i doubt you want that kind of restriction, however.
Agreed I don't necessarily want absolute quiet just tone it down a bit. Is there a muffler in specific you guys are using that will replace the flo through mufflers that came on the speed engineering true dual kit? for the price I'm sure the bullet mufflers that came with the kit can be worth too much
If your exhaust is dumped after the axle then it will always drone. Hopefully yours goes all ghe way out the back. Rasp should not be a problem with dual exhaust. Anyways assuming your exhaust goes all the way out the back, I'd start with good Borla straight-through mufflers. I like the XR1s, but Borla makes plenty of low drone mufflers. Otherwise Magnaflow also makes very good straight-through styles as well. If your system is still too loud for your taste, then Id consider adding cats.
Yessir it dumps in the rear, exhaust goes over axle. Thanks for the muffler advice I'll start looking into both borla and magnaflow this weekend
Texas Speed y pipe with cats is a high flow design. It will eliminate rasp. My car with stock cam, Hookers and the TSP catted Y is downright tame sounding, unlike a lot of off road y piped cars.
Hi flo cats will probably lower it about 10db, not a lot but its a start. I have read that cats can be blown out with FI depending on boost. I have cats with my kooks system and wish it was quieter.
Thanks for the help fellas I went with the kooks green cats, imo the exhaust sounds better with cats. W/o cats I was essentially running straight pipes considering my mufflers are flow-through bullets. Drone and idle is noticeably lower.
I was going to say cats help a ton and so do resonators. Should have gone resonators but either way seems you got it taken care of.
If you still want to tone it down or come across this issue again some time and don't "need" cats, add some straight through resonators. Their specific job is cutting down resonant sound waves aka rasp. Wish I would have caught this thread earlier, they are super cheap. Roughly $20-$30 on the low end and under $100 each for high end stainless. Cats are a huge waste of money if you aren't trying to pass emissions.
When I was 17-18 I learned what cats and resonators do for sound. My first car was a 76 and had no cat, I had a muffler shop take it out and add a straight pipe. I did the same with a couple hondas when I was a teen and it had the same effect. I bet people hated me back then lol.
I was going to say cats help a ton and so do resonators. Should have gone resonators but either way seems you got it taken care of.
If you still want to tone it down or come across this issue again some time and don't "need" cats, add some straight through resonators. Their specific job is cutting down resonant sound waves aka rasp. Wish I would have caught this thread earlier, they are super cheap. Roughly $20-$30 on the low end and under $100 each for high end stainless. Cats are a huge waste of money if you aren't trying to pass emissions.
Hi flo cats will probably lower it about 10db, not a lot but its a start. I have read that cats can be blown out with FI depending on boost. I have cats with my kooks system and wish it was quieter.
Every 3 dB reduction will result in a sound half as loud. 10 dB is a **** load. Did you get 10dB from actually measuring a car before and after adding cats?
Hi flo cats will probably lower it about 10db, not a lot but its a start. I have read that cats can be blown out with FI depending on boost. I have cats with my kooks system and wish it was quieter.
The system as a whole is quieter with cats I know that's the obvious but it also did wonders for the tone in general. The kooks green cats are pricey but they are designed for boosted applications so as far as blowing them out I hope not I'm only running 3-5lbs right now anyway. Guess the next step is to swap the bullet mufflers for some xr1's or ultra flows. This inexpensive true duel exhaust is turning into a 1.5k system anyway... haha I can't stop now I'm already ***** deep. Lesson learn to all who want true duels this $500 system is what it is, you get what you pay for...
Well all the sudden some guys are posting that they have drone with TDs. A well designed system over the Axel should not have drone. I've seen Speed Inc and Kooks and they are good systems. If there is a drone .......... its the bend on the driver's side Not the mufflers or lack of cats.
Drone happens even on Corvettes and Gen 5 Camaros with bullets. You need enough absorbing material to absorb the sound waves. Guess what... F-Bodies don't have a lot of space for large enough mufflers (need a 6" canister at min).
But the issue with the Kooks and Speed Eng duals is pretty simple - they put the mufflers at the end of the pipes. You need the mufflers in front of the axles and a good 2' of pipe after them to really cut the drone. By putting the mufflers on the end of the exhaust, you limit their effectiveness.
I put 6" round, 14" long Dynomax canisters on mine. And it is certainly better. But it is not at all drone-less. It's still insane. And for some reason, my car is louder than most other people's. I was seeing 105db at idle. Now I see 94.
10-28-2017, 12:59 AM
Need advice with new exhaust set-up 
