The Ivory Coast international Doumbia arrived at Stadio Olimpico on Saturday, after a prolific spell with Russian Premier League champions CSKA Moscow - for whom he scored 83 goals in 129 appearaces.
Forward Ibarbo subsequently joined on Sunday from fellow Serie A side Cagliari on an initial loan deal with Roma able to make the deal permanent at the end of the season.
Roma acted quickly to offset the loss of Mattia Destro to Milan last week and Garcia is itching to welcome Doumbia back from Africa Cup of Nations duty, while Ibarbo may be given a chance to play in Tuesday's Coppa Italia quarter-final tie with Fiorentina.
"There's nothing more to say about Doumbia," Garcia said.
"The numbers speak for themselves. At the end of next week he'll return [from the Africa Cup of Nations], along with Gervinho.
"For me, Ibarbo can become a champion, but I have to consider whether he's ready, I won't take risks with him.
"If he can help us [against Fiorentina] so be it, but I have to assess him."
Roma head into the contest with Fiorentina on the back of a fourth Serie A draw in a row as their clash with Empoli ended all-square at 1-1.
Garcia is understandably frustrated by the run, but remains determined to find a winning solution.
"We've got a serious case of 'draw-itis' and we need to sort the issue we have in the first half," he added.
"We're just as disappointed as anyone about our recent run of draws but let's get behind the guys. We'll do our best tomorrow. We've met Fiorentina twice and they're always a quality side.
"To get luck back on our side we need to push even harder from the first whistle. Those who know me will tell you when the going gets tough I just work harder."
