axl911

Anyone added a flapper valve to close off the bypass when you want it quiet?

Blue Ocean

axl,
Bruce in Seattle (Bruce SEA 993) has been working this. You should ping him.

Also, C4S_fan posted a sound clip of stock, motorsound, RSR and LMPP on different cars here http://www.dennispi.com/gallery/Bruces

pstraub

Hi Fo3, just a bump because I can't wait to hear your full report on the LPMM. I just orderer 2' of the T304 2" stainless, getting excited to hack into my stock mufflers (I think they are Motorsound Pkg mufflers, my option list shows 'M159'). Anyway, please give your full report when you have some time. Thanks, Paul

FotoVeloce

I'm reading with muffled ears myself. The idea of a flapper to enable/disable the bypass sounds like a great additional mod. I wonder if there is room to fit one in....

Where did you guys order the stainless from? McMaster Carr or some place like that?

pstraub

Ordered mine from Burns Stainless, it was $11/ft (pn ST-200-16-304), 2" diameter. I had it in 2 days, ordered 2 feet per other posts. Here is the link http://www.burnsstainless.com/304tub...raight304.html

24FPS

so def. not for a cab. i take it.... i need to give robin a call.

btw: fatherof3 the weld job looks great... what a productive day! maybe i'll get a chance to hear 'em @ a future malibu run?

Garth S

You guys are sooooo professional .... buying pipe ... I confess to having scavenged my 1.5" stainless by 'dumpster diving' with a hacksaw in hand ... at a friends muffler shop, which turned out to be the only local source of the correct stainless.

I did the mod last week as noted here , and am more than satisfied with the resulting performance. Leland had originally reported using this size - and it has provided all the enhancement I wanted to achieve.
The motor starts with an authoritative sharp bark , and the exhaust has a crisp, harsh mechanical edge on acceleration, a modest burble on overrun - and zero resonance at any cruise rpm. Actually, it is difficult to detect any difference at highway speeds - until you get into it.
We had a PCA club run last Sunday - and everyone wanted to know what I had done under the hood to get such a great sounding motor ..... cams? .. timing? ... exotic mufflers? ... well, sort of
The LPMM rules!

Father of 3

I drove the car into work this morning (I'm in downtown LA by the way) and I've got to say that the more I drive with the new exhaust, the more I like it. I agree with Garth above, nice sharp bark at start. A low rumble through the rev range. I don't get much of the popping on decel like some of the others report. Also, at highways speed I agree its difficult to discern any difference. What may be a little weird and the reason it took a bit to get used to the change is that I liked the way the OEM exhaust sounds, I just wanted things to be a bit louder. This sound is a bit different. Lower in tone. Like I've said before, a bit supercupish but not nearly as loud. I always thought my OEM exhaust made the car sound angry. The new sound, like I've said above, is growing on me. I think the LPMMs are a keeper. I'll keep updating as I drive more.

24fps, I will be at the Callas tech session so you could listen to the exhaust there.

FotoVeloce

I was about to order the pipe (that Burns Stainless site gives me SO many ideas...) then I read that at least one person has used pipe smaller than the 2" most others have used. Right now I'm not trying to get more power out of the car, just a liiiiiitle more growl. Yes.. it's all about effect over function for this car (the other is all about more power *and* more noise.. ).

Any thoughts on using 1.5" fo a little less volume as opposed to the 2"? Any resonant drawbacks (like loss of torque due to some weird velocity change/disruption? I can always go bigger if I don't get the effect I want. Just wondering what others think about the possible different sizes of pipe one can use.

There is a HUGE scrap metal yard near me too (which is right next to the Naval shipyard here where they mothball and scrap ships.. lots of extra metals lying around....) Mabye I can snag some 304 stainless there on the cheap and my instant gratification instead of waiting 2 days for shipping.. LOL.

Just pondering before I jump in and start cutting up my factory exhaust.

Bruce SEA 993

FotoVeloce,

I tried to figure out how to get a valve or flapper in the bypass and gave up on the valve and how ot operate it. I "settled" for the LPMMs with a curved 2 1/4" SS tubing.

After installing and listening to the mufflers, I am glad I didn't bother with the valve. It would have been open all the time.

The only way it could be valuable to have a valve is to shut off the flow ot the muffler and then you have a super cup or Dansk. Still, the valve and operating mechanism are tough to figure out.

Cheers!

brucec59

For me, with a small kid sleeping when I leave the house, I need to keep a quiet option on the car. So, I either leave it stock or find a way to control it from the dash.

Bruce, after you mentioned you could not get the electric cutout to fit, I contacted QTP for dimensions, but they couldn't give me anything. I recently found a similar product that JCWhitney sells. I have emailed the manufacturer to see if they can tell me the dimensions.

There are times when I think the stock sound is good enough, but then there are times I long for a sportier sound.

24FPS

my thoughts are as exactly as your's were... can't wait to hear!

Father of 3

Ask Leland as he originally started with a 1 1/2" tubing. There was someone also from the UK who used an even smaller diameter who was happy with the results. I can't recall the user name though. I just figured I only wanted to do this thing once.

Bruce SEA 993

bruce59.

I am not sure if those valves will fit. I actually bought some and didn't feel that I could get them in there plus you have the stack of flanges and gaskets and no slip coupling to sandwich it all together. I guess you could weld it in but would it warp. They do have flanges and bolt holes to assemble it with.

Cheers!

HeelToe

I agree. You hardly notice a difference at cruising throttle and sound levels under acceleration are directly proportional to the pressure exerted by your right foot. Thus, easy to stay quiet when in proximity of the "fuzz".

I went with 2" mandrell J-bends, which I suspect is the loudest LPMM configuration and I don't find it tiring or offensive at all. So my valve would also be open all the time.

I'm anxious to hear about the RSR comparison.