VNTGSPD

Doug,

I am VERY pleased with the LPMM mod as the car sounds very aggressive yet refined with the windows down or sunroof open. With windows up, it is just a bit throaty through the cockpit. It makes for a great sound on my daily driver as the sounds is there when you want to appreciate it but is not intrusive.

That being said, it is nowhere near as loud as my '69 with a sport exhaust. If you are expecting to hear it with your helmet on, you may be disappointed. Maybe you could do the LPMM for street use and then make some muffler delete pipes for when you go to the track???

Good Luck!

David

Spuds993

VNTGSPD,

I can almost hear the exhaust now as long as no other cars are near by on the track, so I'm hopefull that this mod will allow me to hear myself over those nearby.

Indeed, nothing beats the sound of the early cars through sport mufflers

jhale

For those of you who have done the LPMM upgrade, have any of you made the modification to the motorsound mufflers? Any experience with the sound? I have seen people making the modifications to the RSR's and others but have not heard any comments regarding this modification on the motorsound mufflers.

Thanks- JH

FisterD

One of the sets I modified was the motorsound mufflers. They belong to "pstraub". To be honest , I don't think there is a noticable difference between the motorsound mufflers, compared to the non-motorsound mufflers after the mod. Maybe Paul will chime in and give his opinion.

MarkD

I am pretty sure the person who started this thread, pstraub, has the motorsound package.
His sound very good to me... though I'm not sure I could tell the difference between my standard with LPMM and motorsound w/LPMM.
You may want to PM him for more detailed commentary.

It's a beautiful noise and not too over the top.

pstraub

I really can't compare my LPMM mod motorsound mufflers with anything. I have yet to hear the standard mufflers with the bypass mod, but I have a couple 993 buddies that are about to take the plunge

jhale

Thank you for the responses regarding the motorsound modification. Based on the replies, I'm a little confused on what the difference is between the motorsound mufflers and stock mufflers, especially if people do not notice a significant difference after the LPMM mod.

I think I'm going to take the plunge and complete this mod this Spring. Anyone in Denver or nearby that can recommend a good shop/welder to complete this job? Anyone else locally want to tackle this mod this Spring?

JH

Wilder

I did this mod a few months ago too. I heard a sound clip with the 2" pipe and they were a bit louder than what I was looking for. I wanted as close to RSRs as I could get as this is what I was going to buy before I found out about the LPMMs. I went with 1" thinking that if the volume was too low, I could always turn it up by going 1.5" or 2". With my current setup, they sound very similar to RSRs. Mind you, I also have a drilled airbox, engine tray delete and big ovals (yes, they do make a difference in sound over stock).

Thanks to Lee and everyone else who gave me their .02 when I was researching this.

Garth S

As I understand the differences, the Motorsound mufflers utilize a shorter case, have differing internal baffles/absorption materials, .... and have a larger internal bypass/crossover pipe ( ~1.5" vs 1") than the stock mufflers - ergo - they 'muffle' less. , and are very nice on their own - preferable to stock mufflers

Having said that, once an additional bypass is welded in, I suspect that the benefits of the motorsound muffler are largely negated .... for the LPMM pipe provides a direct shot from the cat outlet to the exhaust tip, regardless of which muffler it is attached to: as rpm's rise, pressure & volume build - so the gasses and their addicting noise follow the path of least resistance = the bypass pipe.
That is why this mod is so agreeable at highway cruising and in town driving: the muffler remains capable of attenuating the 'normal' gas flow without annoying resonances .... and sits there smiling as all hell breaks loose when when your foot slips into it ... allowing the bypass to do the majority of the work, which in our case = noise.
As many before me, I did the LLPM mod to a spare set of mufflers. You are sure to enjoy the results.

Acropora

Toying w/ the idea of doing this mod w/ some electric cutouts like these:

http://www.badlanzhpe.com/

Still can't decide about dumping straight to air versus dumping into the post muffler pipe and what the affect on performance will be.

FisterD

I think this would be a waste of money. All of those electronic gizmos like that, though cool, seem to be rather expensive. The change with the bypass pipe is more subtle then you would think. Maybe if that was going to bypass the muffler completely, and go to a straight pipe, that would be worthwhile. Not sure if that would gain any performance (probably the opposite), but it would be a serious change when you flicked the switch.

Bruce SEA 993

Acropora,

I played with this idea for a long while...even ordered up the valves. I have several observations FWIW:

I was having a hard time envisioning the fit of the valve between the inlet and outlet of the 993 muffler. The valve is bigger than I thought. I also was having trouble with the stack up of flanges and gaskets and how you can have enough gap to get them assembled and then squish the stack. Both ends are fixed so there is no flex as you tighten the bolts. These are designed for a "floating end" exhaust install an a front engine car.

To get around that fit up issue, I thought that I could dump straight to atmosphere. I couldn't see how that would work as it is so tight in there.

I ended up just going with the LPMM and am glad I did. I thought I wanted it quieter in the cabin for cruising with my wife in the car but as it turns out. the LPMM is not loud at cruise speeds and throttle settings. But, now I can hear it when I hit the throttle. I have yet to be at the track with it and the window open with a helmet on...should be interesting to see if I can hear the engine. Before it was like driving with ear plugs in.

So you might want to listen to one. The trick is you have a TT. There is a whole different exhaust sound as the noise gets "processed" by the turbos.

If you search on variable exhaust you might find a few threads where I talked more about this. Or...PM me or call as this might be better explained live.

Cheers

Spuds993

Whoohoo! My stainless pipe just arrived from Burns Stainless...

FisterD (Darin) shoot me a pm with your address and what time you'd like me there on Friday, I can't wait to get these babies modded and installed!

FisterD

PM sent!

97James993

I just received my 2 foot pipe in the mail today also. Before I have it installed, I have a few questions.
1) Will my car pass CA emissions? (I am assuming so because the muffler bypass is after the catalytic converter.
2) It seems like an easy mod. Can any muffler shop do this kind of work?
3) In terms of sound volume, where does this mod fit? i.e. loudness somewhere between RSR's and Fabspeed Maxflows?