The fiber optics LOOKED nice, and I was tempted to use them but never did. I had a Leaper 4-16x50 scope just waiting for it to arrive, so the temptation was overcame. When I had Gene tune mine, I also had him install a muzzlebrake, 'cause the front sight kinda dug into my palm when cocked....so it had to go.
Oh, and if your friend's TF-89 is .177, tell him to consider Beeman Silver Arrow pellets. They're pricey, but I get the best groups with them out of this rifle. I couldn't get mine to group Crosman Premier Heavies to save my life. His results may/will vary.
Mike