What's up y'all. Just wanted to share my experience with installing my Doug Thorley Short Tube "Shortie" headers and dealing with SMOG inspection in California.
TL;DR-
These headers are CA-legal per
CARB Executive Order D-5470-7. When the smog tech asks for a "sticker", tell them to put the vehicle in a lift and see the EO number on the oval tag that's stamped on the header tube. My smog tech was giving me grief and demanded a sticker in order to pass it. The badge/stamp is visible in the first photo below.
I'll include part numbers below for all OEM parts ordered/replaced with this job.
I bought my '08 V8 in December '23 knowing that it had an incessant ticking noise from the headers being "bad", but I didn't know it would prevent me from passing CA smog. It wasn't clear what specifically was causing the issue- if the headers themselves had cracked, if the gasket had failed- but I knew they needed replacing. Emissions testing all passed, but the smog tech failed me under "Other Emission Related Components/Systems" based on "Upstream exhaust leak, before catalytic converters."
I ordered the headers. DT accidentally sent the wrong gasket set with them, but they were proactive in sending the correct gaskets with express shipping. Much appreciated!
My mechanic buddy was a little concerned about the QC of the headers. He said the machining on the face of the flange wasn't clean, and that the gasket quality was questionable (it actually broke in half when he dropped it into the header shipping box with packing cushion). He ended up using a small amount of high-temp gasket maker between the header flange and OEM gasket before installing.
He also mentioned that there were globs of ceramic coating or some compound on the threads for the bolts that secures the SAIS air tubes. Be sure to chase these before installing the headers as they're pretty difficult to get to.
Per DT's recommendation, I ordered replacement engine mounts since the install requires lifting the engine in order to remove/replace the headers. The old ones weren't in bad shape, but it's a good time to do it while the engine is out of position. We replaced the two air tube gaskets for the SAIS connection to the tube on top of the header assembly.
My 4R was originally imported to Canada by the first owner, who then imported it to the states in Washington. It definitely survived a fair amount of cold weather abuse as evident by the installed block heater and seized manifold nuts to studs. All the studs came out whole, but not one of the nuts broke loose from their stud on either side. Fortunately, I ordered a complete set of nuts and studs as a precaution.
When my mech got the original manifolds off, he determined that it was the frontmost passenger side manifold tube that had completely rusted out and the insert inside the tube had fallen out. The driver's side gasket had also failed. Important note: he said he wasn't able to remove the driver side without pulling the driveshaft.
He test fitted everything and spot welded for the cat placement on the collection tubes, removed it all and fully welded the cats to the collection tubes.
Here they are installed:
My mechanic said this was one of the top three worst jobs he's done, just a huge pain in the ass. At first, he said book quoted 14hrs. Then, based on the instructions from DT, he'd probably be able to do it 7-8. Add in the seized manifold bolts and welded exhaust (previous owner had all the bolts on the exhaust connections welded on??) it ended up taking him the full 14 hrs or so. He also said he wouldn't do this job again for the amount he quoted me knowing now what all it entails.
He confirmed there were no leaks after the install was complete. The day after I picked it up, I went to the smog station and successfully got my smog certificate (see earlier note on how to explain to smog tech exemption for these aftermarket headers) and went straight to AAA to take care of the title transfer and registration renewal. It's driving well, maybe slightly more power and more consistent power through the rpms.
I hope this helps anyone with a V8 in California trying to decide what route to go when repairing cracked headers. The only thing I'd have done differently would have been to also replace the upstream O2 sensors, but given they're pretty easily accessible from the wheel wells I'll take care of those soon.
Here are the oem part numbers for everything else needed for the install:
90080-12008 Exhaust Manifold Stud (x16)
90080-17187 Locking Nut (x16)
17198-50010 Exhaust Manifold Gasket (passenger side)
17173-50030 Exhaust Manifold Gasket (driver side)
17376-50010 SAIS Air Tube Gasket (x2)
12361-50190 Motor Mounts (x2)
89465-35690 Upstream O2 Sensors (x2)
Linear Mode
