Grr said the bear
The problem I had was the instructions are really thin, they should tell you to install the filter to the lower chrome piece first thing . After I did that it was easy to assemble. The performance has been excellent, It says right on the box 25 horsepower and I believe you actually get more and I am very happy with it .
I installed this about a week ago and so far I can't say I have noticed any significant differences. My car displays MPG and it has not changed. Sounds like it has more guts of the line but I think it's just the sound giving you the illusion of speed. If I notice any changes I will change or modify this review.