hello folks; in my 1984 XJ-6 I pryed open and "cleaned" the guts out of the front cataclysm, then had it re-welded and pressure-tested. I also eliminated the "Y" pipe and its secondary cataclysm (the one located under the driver's floor) by replacing it with the European-version of the "Y" pipe, since I was told the car will pass inspection without any cataclysms. It has passed the last three years. They do a visual as well, but since the front is still "there" technically speaking, it also passes the visual. The only complaint I got was about the fuel-filler Seals in each filler door, which I replaced. There has been no damage to the emissions system, in any case the engine breathes better and it responds better and faster, fuel economy has increased. I get about 540-550 miles on interstate long distance driving, at an average 70mph, out of the two tanks. I would say that is very decent mileage. Since I had dismantled the exhaust system, I ended up rebuilding the entire system front to back, sending the new "Y" pipe and the two old, over-the-axle pipes to Jet Hot Coatings, where they coated them with their Sterling (silver and ceramic) coating. They claim reduced exhaust temperatures and rust protection. The parts don't have to be new to get coated. I also used stainless steel Band clamps and bolts/washers throughout. "U" clamps crimp and deform the pipes where they join, so I refuse to use those. No parts were welded together, I used Permatex Exhaust Adhesive in every union, (the equivalent of Firegum, which is not available in the US), quickly clamping as I went. No leaks! The mufflers I found in stainless like the originals, n.o.s., beautiful parts. Now I don't want to use the car so it doesn't get dirty underneath!