Hi guys,
I replaced a leaking flange gasket of my GQ RB30 couple of weeks ago, and it started leaking again yesterday.
I'm guessing,

1) Either a flange surface is warped and pitted badly(not from what I could see though, I saw one end and looked good and shiny, I felt the manifold end and felt smooth and shiny for the most part, warped may be, but I don't think it's badly pitted at all)

or

2) Too much back pressure(I think it started blowing up when I revved above 3k or so.)

I did a Vacuum test. Didn't show up any bad back pressure issues. Muffler appears to be working fine atm.

What else can cause the flange gasket to keep blowing up like this?!?!?

Thanx in advance for any help