Speedmonster185

iTrader: (1)

My duals that i just got (2.5" X-pipe over the axle) have flowmaster single chambered mufflers in them and I have a couple questions about the sound. I'm wondering if these things are happening with other people who have the same mufflers.

First is, there is a spot right about 1500 rpm (a little bit higher now after my tune) where the exhaust gets really loud. It is only for about a hundred rpm or more that it stays that way, then it gets quieter again. It is almost a resonating noise. It sounds kind of like when my Y-pipe was touching the tower brace (is that what it's called?) before I took it out. Depending on my mood I like it sometimes, but other times I don't. It just sounds loud and there is no pulsing noise like normal, it is just a constant noise that is much louder than the normal exhaust sound. I think I can hear it in this clip one ls1sounds:
http://ls1sounds.com/true_duals/TDs_...sup-incar.mpeg


The other thing is rasp. Does anyone still experience this after having changed to duals? Everyone told me there would be little or none with the Hooker, but I had a ton. Then when I was getting ready to switch to duals because of it, everyone told me there would be no chance I would have rasp with the duals, but i still have some. It isn't like it was with the Hooker, but it is still there. It is still in the same rpm range that it was before also. I don't understand why I still have some rasp with the duals (and why I had so much with the Hooker). Do i just have a very raspy engine or something?

My last question is, does anyone know what this exhaust sounds like with cats? I couldn't find any clips on ls1sounds, so if anyone has any that would be great. I'm thinking this might be a good answer to take care of any left over rasp and just quiet it down a bit in general.

Thanks!

skifast87

although i do not have duals. I here the same thing. It gets loud for a few monuments and then goes back to its normal self.

Speedmonster185

iTrader: (1)

Yeah. Not just loud either. It has a different sound to it. Just a sort of drone. It's really annoying from about 50mph to almost 60mph because that is when it is going through those rpms (3.23 gears, a4) and then it gets almost silent just above that at right about 60mph.

skifast87

I wish i knew what it was. I really only notice it in 1st or 2nd gear.

GT Griller

iTrader: (8)

I get some vibrations around 1500RPM but its to be expected since im dumped and cammed, anything after or before that is perfect, i dont get any rasp at all either.....dont wanna be a dick but if ur gonna get bothered by small stuff like that then modding ur car prolly isnt gonna make u very happy.

jmm98LS1

iTrader: (28)

I assume your exhaust is dumped under the car? If so, what you're experiencing is drone at those lower rpm. I get the same thing in my car, and had the exact same drone with a dumped y-pipe setup. That's just the nature of dumped exhaust, it resonates between the floorpans and the ground. Running the exhaust out the back is the only cure.

Because everyone & their brother has a different definition of *rasp* (I here Choco coming, lol) it's hard to tell what yours is. I have zero rasp with my setup, and I define rasp as the "machine gun in a trashcan" sound around 2300-2500rpm. My personal opinion is that the merge itself (an X in your case) has the most effect on this sound. What X-pipe did you use?

I can't recall if anyone on here has catted duals w/1 chambers, but doing so would definitely quiet the system down and take the "harsher" tones out of it.....but what's the fun in that? lol

Speedmonster185

iTrader: (1)

Actually mine is over the axle and out the back already. I'm not sure what X was used either, the guy did a custom job at a local performance shop. I don't know if he made it himself or if there was one that he had already that he just used.

Has anybody listened to that clip? You can hear what I'm talking about in the clip. It isn't exactly the same but it's similar and sounds like it happens at the same place.

Edit: BTW, just to let you know the extent of the drone/vibration that I get, the little sliding plastic things in front and behind the shifter in my A4 buzz when it goes through that rpm, and the cd's in my cd changer in the back (factory one) also buzz when it goes through there.

GT Griller

iTrader: (8)

thats the same buzz i get.....i clicked on the video but it played without sound for some reason.

Speedmonster185

iTrader: (1)

Hmm... Thats strange. So you get that same thing I do? It's really weird that it would only be at those rpms. I guess a stall would solve the problem for me before the converter locks up anyway . lol At least it sounds awesome at WOT .

skifast87

its not that it bothers me at all. Its just i would like to know what causes it.

Speedmonster185

iTrader: (1)

It doesn't bother me much either unless I'm in the mood for the car to be quiet. Or if I'm cruising at like 50mph. Then it gets annoyingly loud and there is nothing I can do about it. Other than that it's fine.

sixvi6-camaro

iTrader: (9)

any flashing on the inside of the tubes left over when they were cut can cause some weird turburlance and noise.. also if there is an exhaust leak it can cause problems too It could just be the resonance and vibrations though.

on a side note.. man get a stall. With those mods you will probably run mid to low 12's even in the thin air.

Speedmonster185

iTrader: (1)

Oh I will . I'll be getting one of those, slick/DRs, and probably an Underdrive pulley too. I'm hoping for at least 12.5's or better on a decent day. I ran a 13.1@106 before any of my intake stuff on a pretty good day. I'm hoping for lower 12's on a good day now that i have my intake, duals, and tune, and I will have a stall, UD pulley, and tires on top of that .

JBIRD02

iTrader: (4)

yes, my 1-chambers resonate bad at 1500 rpm. I kinda like it. I dont have any rasp though.

0utlawTorn

iTrader: (1)

That's just how flowmasters are. They have that sweet spot where you just get a "boomy" type sound. My Mustang with flows did the same thing...

Speedmonster185

iTrader: (1)

Ok. Nice name by the way. Awesome song.

magius231

iTrader: (8)

time to take a lesson from the Mustang guys...

The drone is typical with almost ALL mufflers, to varying degrees and noise levels. Flowmaster happens to be one of the loudest (which is why they are sometimes called Dronemasters) It has to do with the resonating frequency of the muffler itself, you won't fix it without quieting it down a lot. I happen to love it.

Rasp: there are two main styles of mufflers (packed and open) and two main styles of midpipes (X and H). Without cats a packed muffler, which has some sort of filler material in it like fiberglass, will not cause rasp with either midpipe style. An open style muffler like a Flowmaster has no packing material in it. With no cats and an X pipe, there tends to be a lot of rasp with this style...if you want to lose the rasp but keep the mufflers, switch to an H pipe. My 03 Mustang with an Offroad X-pipe and Flowmaster 40's droned bad at around 1700RPM and was pretty raspy, but it still sounded good.

Most rasp can be eliminated with any exhaust by throwing a packed muffler in it, or a catalytic converter. Some people will run a dynomax bullet before the main muffler to kill rasp as well.

2000LS1Z28

OK, I listened to that video and I have no idea what you're talking about within it? Sounds just like any other typical LS1 w/ LT's, no cats, mid-pipe, & Flowmaster 1-chambers cruising around. I will agree with jmm98LS1 though that a true dual set-up like this does have a little drone (especially dumped) in the 1500-2000rpm range.

Also, I know what that mid-range rasp is (from those catless Y-pipe set-ups running into Borlas, Loudmouths, GMMGs, Magnaflows, Corsas, etc.) in the 2200-2800rpm band and my true dual/Flowmaster 1-chambers dumped set-up has absolutely NO rasp at any rpm. My set-up is Kooks 1 3/4" LT's, no cats, 3" H-pipe, and dumps before the axle.

I personally don't think the Flowmasters sound nearly as good run out the back, but you could try adding highflow cats. They'll clean up the sound a little, but be quieter and not as mean. To be honest, I think you should just switch over to an H-pipe instead...

Speedmonster185

iTrader: (1)

I do need to take it back to the shop to get the tips put on, so I wouldnt think it would be too hard to have him switch it over to an H instead of an X. What would be the main differences between sound? And realisticly what would the differences be in power (Im not too worried about power, I didnt gain any time off my ET with the duals compared to Y and catback)? I wonder how much he would charge to cut that piece out and replace it with an H...

5_02ls1

iTrader: (20)

flowmaster drone...lol for some reason the single and dual chamber mufflers do it..all 3 of my cars do it at 1 certain rpm..usually at cruising speed..its just somthin a chambered muffler does