It will tend to be a little louder in the cab with the dumps, but I dont think it is much as long as you dump them a little ways back. I have a 3 inch oval on my silverado, and a 3.5 bullet on my S-10. The S-10 is hard to guage because the turbo quiets it downs alot, but it is really not very loud. But then again it is not real loud with just the downpipe either. My 57 is 3 inch flowmaster 40's and it is very loud. I like the dynomax better because they still have the racy sound without the sharpness of the flowmasters.