phL

The lesser diameter is marginal and wont matter ...

This system bypasses the chambers in the muffler, resulting in more free flow.

ez_ric

I just did this mod over the weekend and it's awesome! It was a bit tricky to remove the small equalizer/vacum pipe in the left exhaust since i don't have a Dremel. The sound behind my '06 CTT is now as deep chested as it should be. The only let down is that from inside you can't hear much of a difference. I'll have to drive everywhere with the windows down which is fine right now during the swedish summer but I probably freeze to death come winter. Worth it, though!

Oh, huge thanks to phL for posting this! I will definitely contribute to Rennlist.

phL

you're welcome.

also, your fuel consumption will go up, since you'll be harder on the gas from now on, to listen to the nice acceleration sound all the time

jeffcatl

Thanks to the op for starting this thread. I did the mod on my '06 S for fun, knowing I could reverse it if necessary. You know what? I probably won't reverse it!!! Sounds pretty nice.

Now I just have to figure out how I can make it switch into stealth mode like the PSE on my C4S. If/when I do, I'll let y'all know how it worked out. Already have a couple of ideas :-)

Shannon123

Fast forward several months.....

Anyone care to report on how this is working out for them ?

still have the setup ?

Is it the same procedure on a 955 CTT ?

Thanks in advance for any thoughts.

ciscorp

Want a Cat Bypass System but without the $650 cost.

Remove the secondary catalytic converter pipes and simply gut each converter. Go to Harbor Freight and buy a Hammer Drill and a set of the Extra Large Drill Bits to drill out the inside of each secondary converter. A hammer & chisel help too. Takes a vise, a little muscle & some time but well worth it.

Also the stock gutted converter pipes still have the support brace for the converter. The $650 aftermarket bypass pipes don't have the support brace and eventually loosen your manifold header bolts from the unsupported weight pulling down on them.

Shannon123

Im kinda just looking for a more throaty sound and I like the reversible idea........

Gutting cats is dirty work.....lol

Jonathon Rolstin

Wow just found this for the first time. I want to do this, this weekend...

amazing.

JR

Shannon123

Any comments on if this mod would pass state inspections in areas like Texas ?

jeffcatl

I've been running with the "insert" mod for a few months with no issues. Emissions testing here involves reading the codes from the EBDCII. I have checked with my code reader and there are no fault codes and all systems report OK. That should be a pass if your test is similar in Texas.

This one is a cheap no-brainer. I love it! My neighbors..... notsomuch :-)
But it's quieter than my 911 with PSE so there is there that.

phL

fastbikes76

Big thanks to the OP !!!!

Just did this today on my UK spec 04 CTT, wow..thats how they should sound

I had the stupid little pipe in the way on both sides of mine but 10 min with a hacksaw blade soon got rid of those. I just used 450mm length of 54mm OD stainless and cut an X in the end so i could tap it into the taper.

Easy DIY job and superb sound now.

Shannon123

Doing this mod this weekend. Any ideas on the purpose of that 'stupid little pipe' (shown on page 1)...do you think its a problem not having it there if you went back to stock ?

phL

i would guess it's some sort of venturi pipe to get (condensation) water out of the bread box.

ndx

Hi Guys,

any ideas if this is applicable to 958 CS ?

Thx