TRD Header Info/Ideas

I installed the TRD header as one of the first modifications after installing the Powermax filter. It seemed like the "thing to do" for improved airflow, but it hasn't proved to be the case. The stock exhaust manifold is quite good at extracting air, and in fact probably provides more low end than the TRD header. Everyone I know that has installed the header has been unimpressed with the performance gain, but in most cases it has remained on the vehicle because it doesn't seem to hurt too much, and allows for more serious mods like cams, pistons, flow work, etc. w/o worrying about exhaust flow.

Below are some things I did that you may want to consider for your header, if you choose to get one:

Studs:
The best thing you can do IMHO is to replace the 3 attachment bolts with studs/nuts. The stock arrangement is 2 studs and 3 bolts, but due to the "imperfect" nature of headers, the bolts can be difficult to align and you run the risk of stripping/cross threading the head, and you *don't* want that to happen. Plus, you can get more even torque on a stud/nut than on a bolt. Simply go to Toyota and ask for exhaust manifold stud and nuts, and screw them into the hole were the bolts go. Getting the header over the studs may be a bit more tedious, but it's much easier than fighting the bolts and worrying about the threads in the head.

Gaskets:
The gaskets provided with the TRD kit should be thrown away, they are useless. Use only a Toyota exhaust manifold gasket, and take the catalytic gasket to a parts store and get a good quality gasket. The TRD supplied manifold gasket will dry up, crack, and fall out in *very* short order... trust me and several others on this one. Plus, the Toyota gasket will seal better.

Springs:
I didn't do this mod, but it has been recommended by many. Replace the springs at the slip joint with ones that are stiffer. You should be able to get them at the local hardware store, just take the TRD springs and match them with something a bit stiffer. It will help keep exhaust leaks to a minimum.

O2 Sensor:
Another mod I didn't do, but has been recomended. The O2 sensor mounting flange has been known to bend from the heat of the header. This will cause the O2 not to seal properly and really mess with the engine performance. Tommy G. recommends building up the back of the flange with weld to support it. If you do this, be sure to do so before you get your header coated!

Coatings:
I had my header coated with Jet Hot ceramic coating, and it did a great job of keeping the engine bay and areas surrounding the header cooler. The header has no heat shields and gets very hot, and this can cause the nearby clutch slave cylinder to get hot and possibly affect clutch pedal performance. Also, you don't want a hot engine bay for cool intake air reasons, and it has been noted on the Digest that the O2 can be affected by the additional heat from the header. The coating was not cheap, on the order of $200 including shipping, but the service was excellent and I'm very pleased with the coatings. In fact, I also had my cam covers coated.

Troubleshooting:
If you install the header and then begin hearing what sounds like a ticking noise on accelleration, it's most likely a leak where the header meets the head. Shame on you if you used the TRD gasket! If you get this try torquing it down a little tighter (since you put in studs you need not worry) and if that won't do it, either live with it or pull it off and have the mounting face milled flat.