timing
If it is off 5 degrees retarded I would think you would not have enough exhaust valve to piston clearance and chance severe damage to your engine.
Most good gear drives, belt drives and quality timing chain sets have adjustment of at least plus or minus 8 cam degrees.
I suggest you consult with a local high performance engine builder to solve your problem before spending any additional money on parts.
It is possible the cam is ground incorretly too.
You need to be within 2 degrees of your spec on intake centerline to get your combination to run to its potential.