Instruct: Classify Amazon reviews into positive or negative sentiment
Query: Adds a touch of red under the hood...

I used this TBS on a 'oo Bravada and the install was confusing using the included instructions. Take your time and look at everything in front of you and how the throttle body is set up and you'll have it figured out yourself much faster. As far as the "whistle", I haven't noticed it. My throttle response has improved, but only marginally. And as far as fuel efficiency goes, I've noticed a slight decrease of 1 to 2 MPGs. I wouldn't say I'm disappointed with this product, but I'm definitely not impressed.