ManAboutIt Posted August 12, 2012 Report Share Posted August 12, 2012 I was thinking of doing a full custom turbo-back setup. Considering eventual N/A cams, bigger injectors, moving up in turbo from the 15G, and an ECU tune...but will basically stay stock until the money is right. I've been to 4 shops so far. Threw down the specs of going 3" all the way (downpipe, cat, resonator where the stock muffler is, straight-through muffler at the rear, and all piping in between). I'm looking for CA smog legality and keeping the loud exhaust tickets away from me, not to mention being all set regardless of performance goal. However, after 4 shops and meeting a cat who got his 855T done, conflicts with my idea go as follows: -2-1/2" will suffice b/c 3" is too big unless I had a huge turbo right off, and I'd probably lose power and torque. -the stock cat can simply be opened up to whatever size piping I use. -custom downpipe may not be smog legal. -turbo cars aren't loud like that to require a resonator in addition to muffler. So those of you who have already had one done, what is the best compromise? Also, O2 sensors have thrown a CEL, so I want them to deal with that too. What would I need them to do there? Link to comment Share on other sites More sharing options...
Dbrunetti6770 Posted August 12, 2012 Report Share Posted August 12, 2012 looking forward to hearing some answers on this as well... sorry I dont have any myself. I am considering doing exhaust, if you find out more let me know =) Link to comment Share on other sites More sharing options...
boxpin Posted August 12, 2012 Report Share Posted August 12, 2012 Bottom line, California rules... if you alter anything from the exhaust manifold to just past the last O2 sensor and get caught you fail. What you can do. Alter anything past the last O2 sensor, even open exhaust will pass. As for the intake side, if you are 95 or lower you can alter the intake, i.e. Rip, FMIC, cold air, etc. 96 and above you cant alter it. What I recommend if you decide to make changes...do a backup. Meaning, have your stock stuff ready for smog time. I swap out my exhaust come smog time. I have a backup. Link to comment Share on other sites More sharing options...
2.3 l turbo Posted August 12, 2012 Report Share Posted August 12, 2012 as long as the pre cat o2 sensor is in front if the cat and 2nd 02 sensor is after the cat it will pass a smog test and should clear your o2 code as well if engine and o2 sensors are working properly and is no exaust leak. other then that you run what ever size pipe or downpipe you want it will have no effect on emissions , back pressure can alter the way your car preforms for example you will make more boost the more you open you exaust the stock tune can only account for so much air Link to comment Share on other sites More sharing options...
ManAboutIt Posted August 13, 2012 Author Report Share Posted August 13, 2012 I'm gonna keep it funky: that swapping out to pass smog thing is too much hassle. I'd rather the sensors remain intact and simply work as they should. Is doing a downpipe that uses sensors exactly where they are just impossible? Do those of you in CA with IPD downpipes have to do all this, or do you smog the car and pass just fine with it on? Link to comment Share on other sites More sharing options...
boxpin Posted August 13, 2012 Report Share Posted August 13, 2012 Emissions wise you will pass but if you are visually inspected you will not pass. I am telling this to you because I live in California and have been sent to the BAR over my modifications. I am very schooled in what will pass and what will not. You can take my advice or ignore it. Just trying to help. While at the BAR I asked many questions. My first BAR visit I failed due to the CAT (aftermarket pictured above) being the wrong CAT for the car. Even though it was a California approved catalytic converter it was not for the car and did not pass. They said I could use an OEM or State approved replacement that was specifically approved for the 850. Not to many options there. I had it all wrong. I thought I had to have the intake system all stock and the exhaust did not matter as much...but it did. The intake is what I could alter, the exhaust could not be tampered with. What I did find out is that you can alter the intake system as much as you want (this being up to 95). So on my next visit I created the OEM exhaust with an angled flange and put my IPD RIP kit back on. I passed. The moment you change out that down pipe its going to attract attention. Sure some California owners have made it through, I was unlucky but learned a lot. Link to comment Share on other sites More sharing options...
NZRED850R Posted August 13, 2012 Report Share Posted August 13, 2012 I have a 2 1/2 from the turbo flange all the way to the back with a flexi bit to a large resonator to a straight through muffler made a huge difference.(had a dyno session before and after fitting + a walbro fuel pump) I think 3 inch will be too loud??. Lucky we don't have to worry about emmissions in NZ yet Link to comment Share on other sites More sharing options...
ManAboutIt Posted August 13, 2012 Author Report Share Posted August 13, 2012 So say I decided to leave the downpipe stock to avoid the risk and just go cat-back. Will there be any power difference or will the car do nothing more than sound kewl? Link to comment Share on other sites More sharing options...
boxpin Posted August 13, 2012 Report Share Posted August 13, 2012 Your goal is to get the exhaust out of the engine as fast as possible. Will it help, yes. Link to comment Share on other sites More sharing options...
ManAboutIt Posted August 15, 2012 Author Report Share Posted August 15, 2012 No one else in CA or a strict emissions state has a take on this? I was thinking of buying a muffler today and just letting it boil down to who can custom build the legal downpipe I want. Link to comment Share on other sites More sharing options...
boxpin Posted August 16, 2012 Report Share Posted August 16, 2012 There are no "Custom built legal downpipes" in California. Also, there are no aftermarket "legal" downpipes made that will pass the California Smog Inspection. Until you accept this you cant move on. With that said you have three choices. I will spell them out. #1 - Add an aftermarket downpipe and cross your fingers and toes that its overlooked when you smog. #2 - Add an aftermarket downpipe and swap it out then its smog time. #3 - Leave it alone. Link to comment Share on other sites More sharing options...
RedStar Posted August 18, 2012 Report Share Posted August 18, 2012 I have a custom exhaust and everything Boxpin told you is true. Here is what I did and what I plan to do knowing that smog is a giant PITA. I got a 2.5 inch back with no muffler. I am in the process of buying a a DP with the plan of pulling off my stock cat and having it enlarged to fit the downpipe hoping that they see a stock cat and assume its the stock DP. I might throw a similar color high temp paint on the DP to help with the illusion. If worst comes to worst there is a pic n pull down the street and they always have 850s. As for not having a muffler I am not sure this is illegal from a smog stand point...im going to assume so but i believe its illegal from a noise stand point. (however I like the sound of it). When smog comes around I will probably just have a muffler welded inline. I just got a 18t in the mail and the nice thing about the 18t is it looks almost identical to the stock turbo. To top it all off I have a ram air intake I made myself which is extremely easy to replace with the stock air box. There is a difference between getting smoged and getting screwed and going to BAR like boxpin did. Smog you have a chance of fooling the guy doing the visual inspection. At BAR these guys normally really know their "stuff". Boxpin I cant believe some cop pulled you over and BARed a volvo. What a dick. Link to comment Share on other sites More sharing options...
boxpin Posted August 18, 2012 Report Share Posted August 18, 2012 Boxpin I cant believe some cop pulled you over and BARed a volvo. What a dick. I didnt get pulled over. I failed my regular smog test because of the mods. I was referred right there on the spot to the BAR. Link to comment Share on other sites More sharing options...
RedStar Posted August 18, 2012 Report Share Posted August 18, 2012 O wow, I didnt know that if you failed you get referred to BAR. That sucks! Link to comment Share on other sites More sharing options...
survolvo Posted August 18, 2012 Report Share Posted August 18, 2012 You will not always be referred to BAR if you fail, unless it was due to modified or aftermarket components. All the info you could ever need -----> http://www.bar.ca.gov/80_BARResources/05_Legislative/RegulatoryActions/Draft%20Smog%20Check%20Manual%202013.pdf Link to comment Share on other sites More sharing options...
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