EDIT: NM my Borla inlet tips are 2.75" and that is a 3" kit so it wouldn't work. I would have to find something different, maybe just an H pipe. Course most of those are all 3" as well.
The Heartthrob should bolt up to your Borla axlebacks fine. They use the proper ball and socket joint so the Heartthrob kit can work with any axlebacks or even the stock mufflers.
Uses O.E. or aftermarket axle-back
I don't have personal experience with Heartthrob but from what I have always gathered based on feedback only, quality is second rate.
From what I have read, I agree.