That's good though, take it back and take it a independent shop that knows Subarus and will not make mistake's and will do it right.
If it's a great shop and they know what they are doing, you don't need a warranty
Try a Tuner shop or a Subaru only type of shop
Last place I'll take it for something that big is the dealer, they want your car out a.s.a.p. What happens when you rush something? You miss and forget something.
Good luck with your car but I would really take it back now and go elsewhere before you owe them $
You don't have to go to the dealer, it's 8 years old