against the head just use the original ones over, or get new ones from lexus(oem). and most aftermarket header/racepipes come with a silver gasket, almost like a thick cardboard material. you can add high heat silicone to assure no leaks. i have done several installs on the is300, and i have only seen leaks when not using gaskets at all(lexluger from nj)

 

yeah i have both gaskets jsut wonder what kinda silicone to use on them, also should i use the silicone jsut on the header/ypipe gasket, or on that and the exhaust manifold gasket as well. what about this stuff:

http://www.outdoorsuperstore.com/st...productDisplay~PERMATEX~ULTRA+COPPER+SILICONE+GASKET+MAKER~productID~473718.htm

 

yeah, thats good stuff. if you go to an auto store, they also make it in black and silver. put it on both sides of the gasket...also helsp gasket stay in place wile bolting it all up. it will smoke a little when first hot and burn slightly off. just make sure you get the high heat silicone. usually good til 1800 degrees or some shit like that

 

hmmm the stuff in the link i post is good for 700 degrees, i thought exhaust gases reach like 2000 degrees or something?? also if i use it for the exhaust manifold gasket you thing it bight burn off inside and fuck up my o2 sensors?