to clarify here is what the plan is.

1st create cats that fit inbetween HE and the muffler to pass smog

2nd create test pipes for running 90% of the time

3rd make any muffler compatible with ssi's work with this install

3th Heat insulation would be heat wrap as there is space. this would be the easiest. set up..

Good luck, you new a CARB number for that exhaust mod. or the bogie man will get you.

Me too, at least with the 86 911.

Its pretty unlickly this will be a production thing but more of a custom make upon order thing so no need for CARB as of now..

man, i have been trying to come up with something like this for a long time. i just couldnt weld, had no talent, cant bend tubing...the list goes on and on...

will you gain more space if the mufflers exited the car from the center like a boxter? damn slick!

I suppose but to be honest this works fairly easily. remember that the only deal to change from cats to street adapters is 4 bolts..

good job Ben!

I'm a happy customer, too!

I think I've seen heat shield products which are made from titanium or stainless which mount to the valve cover. These already exist. Am I remembering correctly? Would these fit? Seems like it would be real easy. Exhaust pipes close to the valve covers is nothing new in the 911 engine. Catalysts are not traditionally this close, of course.

Doug

I'm seeing this for the first time and I love it. One suggestion to even the flow out at the S bends would be to skew the adapter rings. Just cut straight across that gap w/o any bends at all. Maybe even angle the inlet pipe. After all, this is a one-off custom job, right?

I can't wait to see this installed and *hear* about the performance gain. Mark has spared no expense in creating a beautiful Carrera, both inside, outside and internally. This is exactly what I mean when I say "Beauty is not just skin deep."

Nice Job!!!
 

I like the concept, but agree with Milt that by changing the angle of the stubs
on the muffler to about 45 degrees out would eliminate the tight "S" bend. The
extra work on the muffler would offset the construction time needed for the
s bend connector pieces. Plus it would have to flow better! Good Job!

Such a nice idea! It's good to see that one can go fast and not pump out smog. I can't imagine that those would fail visual at most smog check stations. They will look under there, see cats, and move on to the rest of the test. I am assuming the cats themselves are certified??

Yes, according to Ben...

they were certified though I think CA has repealed that now though

Great product Ben!

By the letter of the law they are probably not legal in CA but will probably pass. If I was making them I would sell them with a 'for off road only use' disclamer or look into getting a Ca approval.

I saw someone else doing the same lay out here on Pelican a year or two ago and it is a great idea.

A set of race cats on your RL8 short tube headers in 1 5/8's would probably make more HP as 1.5" dose not seem to be the ideal on a 3.2.

I have wondered about how using a collector that the cat fits on without the typicall, transition down and than back up in size to the cat might work.

A race cat on your 'pre muffler' might have the potental to match this as to mid and peak HP on a stock cam 3.2.

This thread is a year old at least so this may be the one you saw. I have not made any since it was a 1 time build though there is interest and at some point I may do something else. I have some ideas but the cost would be $3500 for headers and cats and muffler so not sure how many would go for that

This is on my to-do list. I have 2 designs drawn out: Ben and I will collaborate on the best design to market.

Yes CA has changed their laws. As of Jan 1, 2010 NO aftermarket cat will be approved to pass CA smog.

What is the reasoning behind that (other than to keep the writers of these idiotic, redundant bills busy)? Isn't the idea to meet the emission standards? Who cares HOW it's done as long as they are met, especially on a 25 year old classic car??