mtnman82

I'm in the land of the crazies too... With a K27, MBC, 3" exhaust with 46mm TiAL, and not having to go on the dyno (just tested @ 2 rpm levels, which definitely helps) I hear one used to be able to get by using stock chips (never get into boost and try to spool up as litle as possible on the way to/from the check). I also hear the state has gone crazy with exhaust systems/cat's, so best bet is a functional stock system. The 3" system, along with what used to be a legal cat for the state, gets questioned heavily, and might only gets passed if you went to high school with the owner or something like that. I believe this year the crazy state went full bore and from now on you have to have an OEM converter, per a list. More crap to take on/off every 2 years.

FWIW, I run a converter regularly. It would be neat, and in the best interest of the state, to be able to test with the exhaust/converter one will run with regularly to make sure one is truly low emission, than test with one converter and run with another if that's what someone wants to do (probably what most Californian Porsches do).

Best of luck with it!!!

PEvans

As near as I can tell OEM cats for the 951 are NLA. I look for used ones, but that is a get very lucky proposition - guaranteed they are old, and most likely spent as well.

The next best bet and maybe the only truly legal one in CA is the DEC cat Tom mentioned. Eventually that is what we will all have.

Follow Tom's recipe (and fix your vacuum leaks). If you read all the CA emission threads here they all come back to that same place. You could leave the cat for last, but figure you probably have one somewhere in your future.

951kaos

I failed emissions testing in BC one year and had to really look for why it failed, as nothing changed from the previous year except for about 2000 miles I drove. Found my electrical system was at fault. The alternator would produce 13.5 v at idle; but under load would only produce around 12v. This would cause a weak spark and cause a fail when it went in for emissions test. I put in a set of platinum tipped plugs and it barely passed. Replaced the alternator and battery cables and had no problem passing the following year.

CO951

I live in CO not CA, but have been able to pass emissions the last 3 times with a gutted cat. 1st time was easy, then they made the standards more strict. There was a lot of tuning done to make it happen, but 1 easy trick we did to lower the NOx was add a couple gallons of E85 to the gas to help lower the burn temp. Once the tuning was figured out it passed easily. The 3rd time I had added a MAF and larger injectors. My tuner said he didn't think it would be able to pass with the changes made, but we loaded up the previous emissions tune and it passed easily again with the gutted cat.

User 52121

Unfortunately for those who live there (or hope to live there), CA is vastly different from CO.

MAF would be an automatic fail, regardless of whether it would actually hit all the right #'s.

JacRyann

Yeah, however, visual inspection is up to the tech doing the test. Some are friendlier than others, most are probably just clueless about the 951's configuration anyway. A stealth-MAF that replaces the AFM would probably pass. I made an airbox that fits ahead of the coolant-resevoir and behind the headlight to encase the open filter and that was OK as well.

Of course this year's tightening of rules may make all that even more difficult. I haven't read the latest regs, but is it true that aftermarket cat-back exhausts are only allowed if they are of the same diameter as stock?

mtnman82

Yes, I believe diameter has to be stock. But I think the diameter part has been that way for a while now, no? My thought Is that they might have more of an eagle eye now as I'm guessing there are being pointed out more details on the CAT...

I'm thinking the 3" system won't fly the next time because of this, even if you know the owner...

Tom M'Guinn

Yes, stock pipe diameter has been a requirement for years. I passed a while back with the SFR 3" test pipe and bullet cat, before realizing that was technically not compliant.

As a very practical matter, I've found you are best finding a smog-only smog shop operated alone by the owner, and go mid-day on Saturday when cars are stacked up waiting for testing. Time is money and the quicker he gets done, the more money he makes, and the more picky he is the worse his reputation. I came to that conclusion once by mistake when I went to a national chain on a weekday afternoon. They had a handful of techs, all of whom were at best indifferent about the results, and they had nothing but time to crawl all over the car and check pipe diameters, etc.