I agree with dave, if you Change anything (oil, oil mix, timing etc) start over with your fuel tune. Also going off what others are running with a similar engine is hard to do unless everything is the same between um. Dome angles and bands play a big part in how much timing you can run without issue. I can see the timing burn on the ground strap and it looks like the engine wants more. I agree with dave I would go to 6 or 7 and try that. Like I said before, make sure ya add fuel when ya add timing or you could burn er down. I also agree with ditching the cdi box and going to a stocker.