Hi All, Looks like financial things may break my way soon(fingers crossed). I have discovered something I have overlooked in studying ZR-1 ads, slightly modified cars. I mean I've seen a lot of ads for ZR-1's that have exhaust system swap outs to headers, most say "original factory exhaust goes w/car". Is the orig. exh. sys. a one piece welded system? If you swap to headers do you need to recalibrate the fuel delivery soft-ware(program)? Sorry, I keep thinking of SB's from the 60's & 70's, lean condition on cyls.6,8,5 & 7, when headers were used. What happens to the O2 sensors and the EGR(?) Sys. and the catalytic converters if you swap to headers? In the old days the exh. gaskets used to leak and the headers used to burn thru eventually, does this still happen? Am I correct in thinking that a street legal header would have all the smog hook-ups like the stuff from SLP(used on the firebirds & camaros) and low restriction cats? I guess I could just limit my looking to box stock ZR-1's; but I've found that people who do the little things to enhance motors usually are strict about maintenence also. I'm not saying that bone stock owners are not strict about maintenence! Thanks to all the members for any light you can give me. Tom