when installing them I remember reading that you had to make something for them, like a seat or something. can anyone tell me what it is, or how to do it?

Make sure they are pushed all the way into the aftermarket rail. I like to use silicone spray to lube them. Sometimes the o-rings aren't a tight enough fit. Judge Ito was showing me some o-rings he found that work well.

Can you elaborate more on the o-rings? Brand, part no., ect.?

the problem is the 1600's do not sit correctly in the intake manifold. What I did was cut a 1/4 inch piece of heater hose(1/2 inch diameter, I think) and slid it over the bottom of the injector, then when you put the rail in the car you will see that hose makes a nice tight seal between the injetor and the intake manifold. Many people have done it, it works well