the only thing i can say is that you'll pretty much get the same result from doing this to your stock cat and buying a high flow one... so its up to you whether you'd like to save yourself some money or not... in some instances punching it out may cause too much flow and not enough back pressure resulting in minor hp loss but this is only in small instances on certain cars. if you want try it out with your stock cat punched out and if you dont like the difference purchase a high flow one then, that way you can test both ways out.