Finally got around to swapping out the advance stop bushing on the MSD #8361 distributor in my Camaro. Silver 25* bushing came out and the 18* black one went in. Bumped up the initial to make up for the 7* mech loss and what a difference in how the car idles and runs off idle. I rolled in the initial as high as 22* while at warm idle and she really liked it. To be safe I settled on 18* initial with the mech advance providing another 18* for 36* total all in by 2800 rpm courtesy of two blue springs. Looks like in order to get the initial up any higher I need to order some different stop bushings. After everything was finished I hooked up the vacuum advance and took a peek at the timing, MSD says their can delivers 10* advance at 15 inches manifold pressure but I'm showing 36* at idle which means the vac can is supplying around 18* advance??? As soon as I unhook the vac can the timing at idle drops from 36* back to the 18* initial I set... At 22* initial I did cycle the car on and off several times and it showed no sign of being difficult to start. After settling on 18* initial for now, I did have to lower the idle slightly and also noticed I picked up 2 inches vacuum - from 13.5 in at idle to 15.5 in. I will say changing the bushing with the dist in the car requires much patience and precise channeling of ones inner zen. I did find that using grease to hold the bushing and washer in place works pretty well while you try to get the locknut started. Had to go buy a short 11/32 open end wrench as it was about the only thing that I could see working to get the damn nut off.