Instruct: Classify a review as either positive or negative.
Query: 40 series mufflers

I am so Happy with my set of mufflers. I just put them on less than a week ago and them with the help of an H pipe and these mufflers my Mach1 sounds loud and has better performance thanks.. It was fast shipping also no problems at all and I am happy with them.. I will really recommend them to anybody..