i just recently got a greddy 4-2-1 two peice header for my civic and an sp2 exhaust. the exhaust bolted up jsut fine and no leaks. but there is a leak between the flanges where the two peices of the header meet. when i bolted it together, i used the gasget they gave me and evenly torqued them down(a buddy who owns a shop told me to let it heat up and loosen it a bit so it changes shape and slowly but evenly re torque the bolts, so i did, and it still leaks. ive had trouble located a gasget that i can replace the aftermarket one with... any help? and also...it leaks out of where it meets up with the cat. i just used the stock gasket so that might be why, should i buy new? or just weld a flex pipe there?