Headers leaking!!!Are they worth the hassle???

I have had my black on black 96 Gt auto for a little over a year now. So far my only mods are FRPP shorty headers, a bassani catted x, custom 2 1/2 inch flowmaster catback, and a k&n fipk. To make a long story short I had a friend help me install the headers about 15,000 miles ago, give or take. Now the headers are leaking, and if any of you have headers on your car you know how much it sucks installing them on a 4.6 stang. I cant afford the $750 to $900 the local shops want to fix my problem so I have decided I am going to tackle the job myself. Basically my question is should I get some better gaskets and put the headers back on, or just put the stock manifolds back on? If I keep the headers, is there a way I can keep them from leaking? Are they worth the emissions issues for a few extra horsepower?( I live in Cali) Any help would be appreciated.

Oh yeah I almost forgot... If anyone was wondering I still have about another year until I have to smog my car again. Also, is there anyone in California with shorty headers on their car that has passed the emissions test without changing back to the stock manifolds? I am tired of these leaking headers making my stang sound like a diesel!!!

thanks for the info.. but I guess what I should have asked is there a way to make sure my headers never leak? I dont want to have to tighten them every couple of months, if they are just going to leak again. Thats the only reason I considered putting the stock manifolds back on. Its almost impossible to get to the bolts without dropping the k member and suspension.