trying to lower ET, time slip and video enclosed

New personal best last week. Got about 8 runs in on Wednesday, best was a 13.61 @102.87. Weather was terrible, upper 80's, humid and da was in the rockies. Not bad for 150,000 miles and untouched. Runs made on stock 245 45 20s and couldnt launch any higher then about 1500 rom or she would spin. Id like to get her as close to 13.0 as possible but i dont think its going to happen without opening up the motor at this point. Only changes to the car is cai, catless mids, mufflers and diablo tune with 2 degrees extra timing and a few other minor tweaks in the boxed tune. I plan to get a custom tune from diablatoona shortly and hope for another mph and 1-2 tenths. Debating headers for a couple ponies and i am seriously contemplating the 3.92 diff package from mancini. Opinions and suggestions?
https://youtu.be/lPINTtGZAqo