ble2011

This is interesting. I think I may find some mufflers on eBay and try it. To answer your question, I would cut and shape the bypass pipe to fit in and around each pipe. Trace the outline of the bypass pipe onto each side. Then, cut the hole in the pipes slightly smaller following the traced line.

TMc993

I did the cut and fit on the bypass tube first. Take your time, cut a rough fit then file/grind in small increements until the tubes fit tightly around the inlet/outlet pipes. Put the bypass tube in place and mark around the bypass on the inlet/outlet. Cut a rough hole and then grind until you have holes slightly smaller that the pattern you drew. This will give you a "lip" to weld to.

Garth S

Beretta - this is good advice! - it is the way I did mine back in 2006 ( search "LPMM:GS1 - with a twist" under my user name.

Make your mistakes on the cross pipe, if any, prior to cutting the muffler: then fit it as suggested above. We call that a "saddle cut" ---- as in the curve of a saddle for a horse.

I used 38mm stainless pipe for the cross over - every Porsche driver that has heard them has commented positively on the sound - and there is no annoying resonance at cruising RPM

Beretta

Yes, this I know, and I was going to do it this way. But what I like to know is how you best draw the halfcirkelline on both sides of the bypass tube, so I can start grinding the bypass.

I want som guiding lines before the grinding.

And what is the best way to make them perfectly straight of the opposite sides?

Hope my crappy english make sense...

bobboinski

I took cardboard tubing that fit snugly over my bypass pipe, trimmed it to fit, slid it over the bypass pipe material and marked my cuts. Easier than trial and error with stainless.

TMc993

Honestly, it was a lot of guesswork and cursing. I bought 3 feet of pipe, cut two sections roughly to length, then used the cross-section of the remainder as a pattern for the first rough cut on each end of the bypass sections. I made the rough cuts with a torch, then used the grinder and a lot of guesswork and fitting to finish the cut. The first one was a pain in the ***. The second not so much. Cutting and finishing the holes in the inlet and outlet was actually more tedious than the bypass pipes because there was no going back if I screwed up. I have a friend who owns a welding shop who helped with the torch work and the did the final welds for me.

Beretta

Thank for all info.

It took me 2 hours to grind today.

Used the grinder and compressed air tools to do the job.

Here you can se my progress. The tube is 2" wide.

Hopefully we can weld it soon.

Regards the Swede.

csmab

You will like the sound. Just enough extra to let you know they are not stock but not too over the top for highway cruising.

cgfen

LPPM mod rules!!!!

FTW!

Here shown on 997.2 cans

Soon to be back on my 993 also

TMc993

You were faster than I! Very clean work!

Busta Rib

With this thread, I finally understand what LPMM means now. Thank you! Looks like a great mod.

Beretta

After welding, I hope I can show you a video clip.

Beretta

Here is the clip of the LPMM muffler overhaul!

911PERVY

Very nice and good to see Layland Pete gets the credit for the first person to do this, unlike other people taking credit as their idea!

TMc993

Sounds about right!