Yeah 6 bills is a lot. But it is the factory and that is always costly. Get yourself a carb legal header and do it yourself. It should be name brand, cause most carb legal headers are. DC Sports, Greddy I think...I believe you'll need a 12mm socket for the head bolts, and a 14mm socket and open ended wrench for underneath where the header hooks up to the cat. Get yourself a new exhaust manifold gasket and donut flange gasket just to be on the safe side and have a good install w/no leaks. Let the car cool down real good, jack it up, stand it, remove the heat shield, spray all areas to be loosened w/WD-40 wait about five minutes and have at it. With the stock manifold there is going to be some brackets that add more support, you won't be using those so just take them out. As for the o2 sensors they should be in your cat not your manifold, so you should be good there. When putting those tension springs back on underneath use small zipstrips to keep them compressed while you put them back on. Then once you get the nut and bolt together, snip them free. Good luck!!!