Seems like a lot of whining about a non-issue here. Nobody has said anything untrue on this thread except your early claims the new design manifolds solve the cracking issue. I don't understand your attitude here, but you're ruining a lot of the chance you have at a sale by being abrasive and rude. Everyone has said your price is fair and wished you luck with the sale. You're making the situation worse by insulting good folks on here who are known quantities. It makes you look like a problem, and nobody wants to get involved with a problem.
Settle down and let the process run. Manifolds are something not everyone needs/buys all the time, and it's going to take the combination of yours being available and someone from an emissions state having a need to get them sold. Until then, you'd be well advised to take a step back, put your pride aside, find some civility, and stop bashing people for correcting your mistake early in the thread. It's up to you whether you can take constructive criticism and change the tone of your posting, or just stay ticked off and attack me, too. But so far, nobody but you has done anything ugly on this thread. You posted false information, known to be false to most of the guys on this forum, and somebody politely corrected you, and you've been rude and combative since then. Maybe acting like an adult, thanking people for providing information you didn't have, and being patient while you wait for a buyer would be wise.