I figured I do a quick write up on my install of a Thorley Header on a 1992 Sidekick 2 door 16L 8V engine. Bought the Header from RRO and received it without any damage. It is nicely chromed but in the instructions they do note that it is a protection chrome and not a finish chrome and that it will change colors. I cut my exhaust down below to free up the manifold (did not have stock exhaust). Put some wd-40 on the manifold bolts and let it soak while I removed the intake hose. There is a bracket at the top of the manifold that goes under the intake that has to be removed and will not be reused. Luckily all the rusty nuts came loose with my air ratchet. Removed the manifold and gasket. I used a wire brush to clean the head although it probably didn't need it. Then mocked up the header. I came accross a big problem. One of the pair of tubes on the header did not have clearance for a stock bracket that connects from the transmission to the engine. If I hadn't mocked it up the bottom of the header would have never sat flush with the head. Initially I tried hammering that section of tube to try to gain a little clearance but it wasn't enough. I had to take a 1.5" sanding drum on my drill and notch about 1/4" to 1/2" of material off that bracket to clear it with the header. This was a slow process as I would grind, put header back on and check clearance, remove and grind some more. Once it mocked up well I installed the gasket and mounted my oxygen sensor in the header and then attached the header. This was when I came against my next snag. The wire for the o2 sensor is not long enough. I cut some of the stock zip ties to gain additional length from the harness and got it connected behind the factory shield that is in that area but its along side the steering shaft now and eventually I am going to have to disconnect it and solder in some wire to extend it. No mention of either of these snags were in the instructions so hopefully this will help with someones planning process. The flange included with the header is a 2.5" pipe. I got that welded to the rest of my exhaust which is all new and includes a 2.25" cat, 2.25" resonator, 2.25 thrush turbo muffler, and a reused section of pipe at the rear which is 2" from the muffler back. First impressions are awesome. I had read some people stating that their header addition made their zuk run smoother. I definately get the same impression. The idle is very smooth and the power under acceleration is smooth. My exhaust does a nice quiet gurgle at idle and definately has the flowmaster sound. You can tell it is much more free flowing. My manifold had a leak so this is actually a much quieter setup than previously and has a nice low pitched growl. It does feel like it has more smooth low end power. Nothing that will blow your socks off but I am happy with the outcome. Of course on my 31" tsl any power is soaked up. :^) My original manifold had a hairline crack around the front tube and the flange to the downpipe was severly warped causing a leak. If anyone else is having problems with their manifold setup I would recommend the swap to the header just be prepared for the two snags above.
