It kinda suprises me too, I thought the 3100, 3400, 3500, 3900 were all based off the same basic engine. I find it odd that they would have changed the bolt pattern for the exhaust manifolds with the newer years.

Why do you say that? If all he needs is 10 people to email him saying they'd like him to start making them- then go start 10 new email accounts and email him.

Even if what he really meant was he needed 10 people to put money down for a group buy like normal- there are tons of cars with 3500s, its just a matter of you going to the various forums and getting everything together.

Trust me, if they managed to find 30+ people to put money down for headers for the much more rare LS4 cars, then I'm sure you can find a measly 10- you just need to get all of the details (ie material, sizes, exact price, timeframe) sorted out with the vendor before you try and start a group buy.