I read that stock variable muffler opens the second stage thrue the left muffler tip after 2000 RPM, this is with a butterfly mechanism. Testing this today I noticed that mine opens at wide open throtle only. Even if I rise the RPM slowly to 4-5000 it wont open.I WONDER IF MY MUFFLER IS WORKING PROPERLY?
Can you Guys do this test and post the results, thanks!
(Youll need a helping hand to feel the tips thrust)

By the way, does anyone knows where can I see the ilustration of this system, Ive seein it somewhere and cant recall where.

 

I think it only works at WOT. Notice next time U take off. if U take off at lower RPMs vs around Say 3K or so. the car seems to take off faster and feels like its got more power. The sudden push of air prolly opens the flap and holds it open through WOT.

 

Yes..the system works on backpressure. The engine needs to be under load for it to open at 2000 rpm. At idle, youll never see it open by revving the engine.

 

While going for a ride on Sunday after a good WOT run, when slowed down to a stop, the sound of the muffler was different, it sound like an aftermarket muffler louder than normal, open it again and it came back to normal quiet. I think that might be the butterfly that opens the second stage might got stoked up open. It worries me that if it got stoked open as well might get stoked close and that might cut performance. Any one backs my theory?

 

Better it get stuck Open then close. if It get stuck open then U don't need to spend $550 and get a STEALIN Exaust
KEV Did that STEALIN exaust really give U a HP Gain or what?? I'm begining to wonder now. The Y-pipe gave me some power under the pedal, thinking if that $550 is worth another 2Hp gain??

 

I instaled the Stillen Muffler and my car got notisable slower and much louder, I took it off the very next day, I lost lots of $$$. I do have the Stillen YPipe. My car is Auto. Trans.

 

Yeah I noticed that when you give it WOT the noise is different. In WOT it sounds lke a euro car (it has a kind of whistle??? well sort of. Sounds cool.) Under normal driving it has a low,deep woooooooooooooo noise. I like it. Inside the car it sounds all the same. It has a rrrrrrummm noise.

 

The illistration of how the stock muffler by-pass works is located on the nissan website http://www.nissandriven.com Click on Maxima, then click on Performance, then click the third circle down that shows the muffler by-pass valve. There is a short vidio clip of the by-pass valve in action.

 

does this mean aftermarket mufflers w/o this will loose power in the low RPM/load range?

Jeremy
2k 5sp SE

 

If you have a huge B-pipe or exhaust, the increase in air capacity may result in a loss of back pressure. This will take away some low-end torque and low-rpm horsepower. However, you may gain a little bit on the high-end.

 

When you say your car got noticeably slower with the Stillen Muffler, did it do so at both 1/2 throttle and WOT? And is the Stillen muffler baffled or straight-through? Reason I ask is because I've got a 2-1/2" mandrel-bent custom catback exhaust system attached to a 24" Magnaflow muffler (straight-through design). I've noticed a very slight decrease in performance at lower speeds and less than full-throttle. But when I'm at higher rpms and WOT, the car definitely pulls better.

 

Yes I felt the car slower all the way, I dont know if the combination of the Stillen YPipe and the muffler together affects, but anyway in my case yes it was slower. Thanks to the good guys from Stillen they accepted the muffler back, but I loose lots of $$$.00 in the two way S&H. I even tried the Radom Cat and it didint work, so I think the exhaust sistems in this cars are a bit touchy. About the YPipe, it helps but you need a good tail wind to feel those 15-20 horses they claim! Take care.

 

Actually the gain is in the midrange toppend. According to the dyno charts the gains start around 4500rpm and up. Its kinda wierd because in the 4th gen's they gain power from idle to rev limiter.

 

<img src="http://integra.vtec.net/geeser/megamax/images/2000_exh_chart.jpg">

sure.

 

I've decided against installing a Y-pipe for a couple of reasons, not the least of which is remaining smog legal. I don't know what the penalties are here in California for removing catalytic converters, but I imagine they're pretty stiff.

There is some drone with my catback exhaust system, but it occurs primarily between 2000 and 2500 rpm, a range I don't normally drive within. The exhaust tone is quite mild at cruising speeds above 2500 rpm. And at least now I don't have to look at the tach or reach for the shifter to figure out what gear I'm in when I'm driving on the freeway.