followed your monster creation a while back great work on that.
I also have a LN3, there is deffinate restrictions in the manifolds(I had seen a set laying around at a friends one time), and with your setup you could deffinately use that extra flow. I will be taking mine off, and porting them. Also I am going to get them ceramic coated so they no longer look like garbage and produce less heat. I don't know if it will fix your problem but with what your running it would deffinately help. just my 2 cents anyways good luck!