1994 F350 5.8L 2WD DRW Crew Cab

I'll be installing longtube headers (OBX) and dual exhaust all the way back, exiting in front of the rear wheels. I'm wondering if I need flex couplings behind the headers. I'm thinking of stress on the header bolts and tube welds at the flange. Is this a valid concern, or can I just weld it solid the whole way?

 

you should be installing hangers for the exhaust. if done properly by a shop you wont have to worry about the stress put on the headers. Run Percys gaskets and 1" long headers bolts to reduce the risk of the bolts backing off. put about 100-200miles on the truck and then recheck the bolts.

dont forget you will need to run either an x pipe or an H pipe and a hi flow cat for both sides. I recommend magnaflow, they are only about $60 a piece

 

The vibrations I was thinking of are engine torqueing and general road bumps, etc. So, they're not an issue if the rest is hung well? (no pun intended...)
The H-pipe is another question... is it for improving flow or just for sound quality?
I was going to skip the H-pipe. But, would it go across before or after the cats?
I'm gonna use Magnaflow 2.5" cats and mufflers. $50 each, as you said.

 

You can run it solid all the way back, thats how mine is setup, and i wheel the **** out of it. Never had a problem yet. H pipe is for performance, but it only comes into play in the upper half of the rpm band.

 

you can run an X pipe also. like mentioned it helps performance by scavenging the exhaust. you can have it before or after the cats thats your choice. i would put it after the cats. run these ideas by your exhaust shop, they will steer you strait. just dont go with out H or X pipe.

 

Your exhaust system should be able to support it's self without being bolted to the headers. Good quality hangers will help reduce drone. It would be really easy to but a H in where you bring the pipes together just before the cats. You could but the O2 sensor in there too.