Hope’sPonyCar

Manifold outtake pipe broke just before the flange that joins it to the cat intake. I’ve removed the manifold but breaking the two 14 mm nuts holding the flange on has been quite the chore. Been soaking with rust breaker, wire brushed em and scraped around the edges with a screwdriver. Tough to get good leverage to ‘break’ em.

ZEN357

WD40 them and let them sit and keep doing it for a few days. That's all I got. Good luck on getting them to break loose. Welcome to working on the latest muscle cars where they make it so you can't work on them. Are you replacing them with aftermarket shorty headers?

Derf00

Make sure the bolt itself is not turning with the nut. If the knurls on the bolts have stripped, the nut and bolt will just spin together. If that's not the case then some light persuasion with an impact gun does wonders to break up the adhesion from rust and corrosion. You can also get some similar results by hitting the ratchet handle with a deadblow hammer a few times but it's not as effective.

Do not get MAC shorty headers if you have small AIR tubes coming off the manifolds. They are 3/8" hard lines that screw onto the exhaust manifold with a compression fitting on the drivers (and I believe passenger side) manifolds. They are emissions related. MACs fitment is crap and don't seal correctly against the factory emissions pipe so you end up with an exhaust leak.