I just completed this install and I thought it might interest someone here. ('83 El Camino Choo Choo SS with '96 Impala SS LT1 engine/4L60e transmission.) I installed this engine back in 1998 and up to now was running the stock 305 exhaust manifolds and single exhaust. The headers are Hedman 66609 shorty. They fit this combo very, very well. No out of the ordinary issues at all. Stock spark plug wires work fine. I am going to have to get a new A/C compressor manifold and make new hoses but I don't think I will have any issues. I'm going to redo all the A/C lines and upgrade to a parallel flow condenser with the outlets on the passenger side. Already bought it and just need to put my hose order together. I'm going to use reduced barrier hose for an easier install at the compressor. It will be tight quarters there. The exhaust system was a lot of work. Very time consuming. Don't anybody think this is easy because it's a kit. It takes a bunch of fitting to make it go in perfect. Many iterations of mocking up and adjusting connections. I've got lots of hours in this. I did do a couple of things that made it harder in that I used shorty headers and about the largest muffler that can fit into the space they go in. (They are Dynamax Super Hemi Turbo mufflers 17748.) I also cut off the tailpipe tips because Pypes angle cuts them and I didn't like that at all. I put straight cut ones on and polished them too (had enough extra pipe for them). For making the custom angles behind the headers and at the rear of the mufflers, I used a U bend in 2 1/2" stainless that I bought from Jegs. I cut them and then ground them little by little in order to get the angles I needed perfect. Every joint is welded and since I didn't use stainless wire, I painted all of them with ceramic exhaust paint so the welds wouldn't rust. I welded in a V band clamps in the rear of the mufflers. I also put hangers in front of the mufflers for support. Can R&R if needed. Just connects in 3 places (headers, hangers and tail pipes). A floor jack at the balance point and it's very easy. Moved the shift rod to the outboard side of the swing arm and ground the head of the bolt a little for extra clearance. No problem at all. Did not cut ground clearance at all: I'm not ready to start or drive the car yet. I've got the gas tank out and doing some upgrades there. I'm installing an in-tank pump. I'm also replacing all the gas lines as I didn't like the way I did them when I originally installed the engine many years ago.