I just installed an entirely new exhaust: WSP mandrel bent Y-Pipe, replacment Catco Catalytic converter, WSP 2.25" mandrel bent 'B' pipe w/resonator, ending in a Magnaflow Street series #14830. Used all stock Nissan hangar rubber, no pipe contact with car underside anywhere. I've read most of the posts on mufflers; but nonone seems to have encountered an exhaust this radically loud.

Tone is Great, but Way Way too loud. Interior resonance is intolerable at highway speeds with windows up. With even one window partially down, sound levels go up 300% and will vibrate the fillings out of your teeth when exhaust hits certain resonace points - like going uphill at 65-75 mph in 5th gear (2500rpm -3000rpm). Tremendous reflected noise from under the car reflected off the pavement and the car as well as from the rear. Sounds about like a V8 with headers using only after header glasspacks and no pipes.

Magnaflow says that's what they would expect from the Street Series when upstream high performance components are used on a Maxima; is much quieter/mellower when used with Maximas with upstream stock exhaust. They recommend their XL series, but not the XL3 3-chamber. They say XL3 will sound lousy with a V6 (is for trucks and RVs).

Also called Flowmaster - they recommended their 50 series, 35% quieter than Magnaflow Street, but to expect some interior resonence. Asked abut 60 series, but they claimed is no quieter but will sound crummy with V6. Said 60 series is for 4 cyl.

I'm a little leary of both, as they are straight through designs.

Do any of you using aftermarket Y-pipes and/or high flow cats and B pipes have sugestions other than going (back) to stock replacment muffler??? I would enjoy a louder than stock, healthy sounding exhaust, but not the current Flowmaster - I'm goin to ditch it very soon.

Sorry dude that sucks. I've got a stock exhaust except for the Y-pipe. I think you might need a bigger resonator?

I'm in the same boat. I'm going to try installing a larger resonator first, as the one on my car is pretty small (less than a foot long). If I double the size I am hoping it will reduce the decibel level as well as the drone, while maintaining the deep tone. If that doesn't work I might have to get a sliencer for the muffler or maybe go back to a 5th gen muffler.

My resonator's pretty long, maybe 20" case length. I've thought of trying a better resonator - like a muffler; but not much more room in that part of the exhaust tunnel - can't handle a much bigger casing diameter. Plus, the entire Magnaflow casing HAS to be vibrating (resonating) to get that noise from all directions other than staight rearward.

Same boat here. WSP Y & B pipes w/resonator. Car Sound Cat, all in 2.5". Have an Edelbrock RPM series muffler. Was supposed to be quieter then other free flow mufflers. It was intolerable. Tried a Magnaflow 12158 which is a 14"x8x5 2.5" single in/dual out and that was even worse. Went back to the Edelbrock and put a 2.5" chrome tip resonator on it. It is now "tolerable", but it's still not what I want. This is a daily driver and I want performance, but without that horrendous fart can noise.

What size inlet does the 5th gen muffler have? I'm actually thinking of just getting a shorty OEM style truck muffler and trying that. I'm sure the OEM style muffler has a lot more resistance, but it can only be 14" long. it's 2.5" in and out which still flows WAY more then then OE pipes did and it'll be quiet.

Pretty sure the 5th gen muffler inlet is 2.25". However, it is a side inlet and so you have to hack off a little of the b-pipe and bent a pipe over to the inlet. My mechanic did it for $20, it was pretty easy.

hey man i didnt even go with flowmaster or magna flow i went with the g-reddy cat-bak and all i have to say is wow. i love it is in no way a ricer muffler but has the tone that i love and its even better at wot. I would say go with g-reddy but i dont know if your in the market for a cat-bak. aslo i did put in the warpspeed y-pipe.

get a long **** resonator. it help shut up the drone on my magnaflow. i think the resonator i put in was 24 inches. good luck

Thank you ALL your comments! They proved to be invaluable in helping me solve the problem.

I swapped my Magnaflow for a Flowmaster "50 series SUV" muffler and that did the trick. Nice deep tone, thought not quite as velvety deep as the Magnaflow, but interior drone & teeth rattling resonance is GONE. It can still be heard inside during highway cruising, but with the sound coming ONLY from the rear and volume just over the regular highway road noise. Exterior exhaust noise was reduced by around 40-50%. Considerably quieter on the outside, but gives nice roar at WOT that says "Get out of my Way" without evey cop in a 3 mile radius hearing it. Stealthy enough in normal driving not to attact attention from the Police.

The Flowmaster has a much larger casing than the Magnaflow, but still fits the 3rd Gen just fine. The Flowmaster splits the exhaust flow into two paths of different length then rejoins them so that a lot of the vibration and noise is canceled out. I don't believe I'm giving up any flow over the Magnaflow; this muffler is designed for big block V8s in SUVs, so has plenty of flow capacity for a modified Maxima.

I'm now of the opinion that the Y-pipe, B pipe, and high flow cat increase the exhaust gas velocities so high that the entire Magnaflow casing vibrates like crazy, and passes this vibration along to the rest of the exhaust piping as well. The effect is to cause all these parts to
act like a speaker which generates all that noise coming from underneath the car and radiating off the pavement.

i think i could possibly be experiencing the same thing. ever since i've had the new exhaust system put on (2.25 or 2.5 inch all of the way back from the turbo) it seems like the it is much louder. I guess I won't really be able to tell till I get the car running correctly and get it on the road but I hope I don't have to change the muffler.

hehe it would most likely drone like mad if it's a straight through muffler

well i have one of the oval ones so there should be quite a bit of material in there to muffle it.

Your turbocharger should eliminate most of the problems we're having here with exhaust resonance on NA engines. One of the advantages of a turbocharger is that it eats up lots of energy from the exhaust gases to compress the intake air, so there is not anywhere near as much energy left in the downstream exhaust gasses to cause noise and vibration. The turbocharger also acts as a buffer, smoothing out spikes and pulses coming from the cylinder exhaust strokes, and returns a much smoother flowing gas steam to exit down the exhaust pipes.
You still need a free flowing exhaust for max performance, but I wouldn't think vibration and noise would be anywhere near the same problem as a high performance exhaust sytem on a NA engine.

yeah, i figured that turbo would help. guess i'll find out soon, hopefully.

i will win and nobody can stop me. everyone said it was loud, but I must see for myself.


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