The 40-year-old sits three shots adrift of joint leaders Matthieu Pavon and Max Homa after backing up his opening 68 with an accomplished 69 in Sun City.
Ramsay, who started the week four places adrift of the cut-off for next week's DP World Tour Championship, began Friday with a birdie to climb to five under before holing from 35 feet for another gain at the seventh.
He finished the front nine by picking up another shot before salvaging an unlikely birdie at the 13th when he chipped in from 89 yards after finding the bunker with his tee-shot.
A bogey at the 16th was his only blemish of the day and Ramsay admitted the mental challenge set by the South African layout means he relishes the battle in Sun City.
"The game is really good, I just need to be dialled in a bit on my process, which makes me hit good golf shots - a couple of small swing thoughts just focusing on that and if I do that, I can be free and hopefully the scores will come from there," Ramsay said.
"This golf course is different to the normal ones we play because the sections are so severe on the greens, so you may have 150 to the front but you could have 175 to the pin and you might have to carry it 170 and no further than 178 so once you drive it well, you have to be dialled in with the irons.
"I love it because there is no giveaway, absolutely no giveaway. Anyone who wins this tournament, or has won this tournament, has had to work really hard, probably play the best golf of the field, not just putt the lights out and you win - every facet of your game is tested and the mental game is probably the biggest thing out there.
"It makes you feel uncomfortable, but I kind of like that because it puts pressure on you. I love that there are some tee-shots out there where you stand up and you might have crosswinds, and you're like 'I have to hit a golf shot here' because there is nowhere to hide. It's fun, but it tests you at the same time."
Dan Bradbury was the overnight co-leader after the first round and would have held that position at the halfway mark if he had not bogeyed the last after a topped drive, which eventually led to finding the greenside rough.
He produced brilliant wedge shots at the 10th and a hole-out at the 15th which saw him join Pavon and Homa as co-leader, but a bogey-birdie-bogey finish saw him drop one back of the leaders.
However, he is looking forward to playing with the American, who is the World Number Eight, on Saturday as he aims to secure his second DP World Tour win in his maiden campaign.
"Overall pretty happy with the score," Bradbury said. "Definitely moments I want to try and avoid tomorrow but a lot of good golf in there and a lot of fairways so if we can keep it in the fairway then that’s fine.
"When you’re playing the course this way round, nine through 14, you’ve got chances. Starts getting a bit tougher again from 16 in. You’ve got a little five-hole stretch there where you realistically need to be two or three under, there’s three par fives, all reachable, you’ve got to take advantage of the par fives.
“I’m looking forward to it. I thought that putt might have cost me the last group but back in the last group tomorrow, that’ll be nice playing with Max for the first time. Top ten player in the world, this is what we try and do and I’ll just go out there and keep doing what I’ve been doing.”