I installed TTI headers and their 3inch duals, onto my 68 Barracuda(360/4spd). The rear end was narrowed, and the springs moved inboard with the offset kit. This to fit 325/50-15s inside the factory tubs. The car was lowered a bit so the wheels are actually in the tubs, but just barely.
The fueltank is a stocker, and the TTI tailpipes thread the needle just right. But
forget about the factory tips which IIRC fit on 1.875 pipes.
I ordered my 3"TTIs with 3"turn-downs.
If you are looking for the 340 sound, you need the whole enchilada; that is to say; the 10.5compression 340, log manifolds with working heat-riser, the 340 cam, the small pipes, 3-pass walker-type mufflers ,and of course the tips.
If your 340 has an aftermarket cam and headers, then the growley 340 sound is pretty much gone, anyway.
I have 2 1970 Darts with the spring relocation kit installed. I used the standard 2 1/4 inch pipe pieces from Accurate Limited (who do not, by the way have proper 70 Dart tips available) and the pipes fit fine, but I had to put 4-5 washers between the rear insulated hanger and the frame to get proper clearance between the pipe and the rear shackle which is offset. I also have a car without the relocation kit - stock location - and used the exact same pipes. you would have to have cyborg laser distance measuring in your eyeballs to ever be able to pick up the difference by just looking at it. I'll post some pics tomorrow.
You are talking about the 3/4 inch relocation and not the 4 inch relocation right? If you move the springs in line with the frame, as opposed to up against the frame, you would be better off to take the end of the tailpipe over the spring and have it come out on the outside of the spring if you want something close to stock tip location.
So here are pics of my 70 Dart with Accurate Ltd. pipes. The washers at the hanger/insulator move the pipe in 3/8 of an inch. This picture is taken with the car on a lift, and the hangers rotate down and closer to the pipe when it is on the ground - make sure you install the hangers with the nuts away from the pipe!.
Just to clarify (since looking at it this morning) the original tail pipe ends and tips are directly under the frame, so if you move the springs under the frame they are right where the original exhaust location is...
I used 3 1/2 inch pipes to the mufflers and then 2 1/2 tail pipes so if pulled over by the Police they could hear and feel the exhaust out the back. The car wasn't that loud considering it dumping 3 1/2 in front of the rear. Tank was narrowed 3 inches on Passenger side and I use 3 inch aluminum spacers on the tips
I have Accurate pipes and tips on my 1973 Duster. The car had the 4” (mini-tub) relocation. The housing mags are not tubbed so it was kind of a waste of time for the previous owner to have put the springs under the frame. Maybe he was going to get around to finishing the tub job.
Regardless, I got the car and wanted to use the factory style exhaust and tips. The tailpipe is supposed to run right along the gas tank on the passenger side, right wher the relocated spring was. I had to move the springs. I do plan on putting a 1/2” Doctor Differential relocation on when I build my 8-3/4. I should still be able to run my Accurate exhaust.