I think you can tell a difference, but most of it probably came from cutting 1/2" off the other end of the manifold. I used a carbide dremel bit. Be carefull, I have done 5-6 of these and have only ported thru on 1. Check out the weld on your manifold and make sure you have enough material to cut from. After you rough it in, start polishing. I used the cut off wheel attachment with a small cotton wheel, and dremels polishing compound to smooth things out. It gets hot so wear gloves. The whole process takes better than an hour (cutting, porting, polishing,ect.).