City have signed Jazz Richards and Frederic Gounongbe during this summer, with Kenneth Zohore and Lex Immers joining on permanent deals.
Trollope did not reveal which positions he wanted to strengthen, but said he was keen to add to a "few areas".
"We are still trying to add one or two new faces and maybe one or two going out as well," he said.
"With the emergency loan window no longer at our disposal, I think it will be a busy three weeks for a lot of people.
"A lot of clubs will be in the same situation. There will be a lot of movement.
"I've got a real good feel about the group and what we're capable of.
"We know it's a strong division with some big clubs in, but if we can add in a few areas we think we could compete."