If you upgrade the exhaust with the Super Six setup like Chrysler did NOT, you will feel a noticeable difference. Also, I dare you to tell a NASCAR driver they cannot tell ten horse power difference. Chrysler put a larger head pipe on SOME Super Sixes, but they failed to use an exhaust manifold with a larger outlet, so "all that" still had to go through a 1 7/8" hole. I had mine enlarged to 2.5" and ported and I can tell you I can tell a big difference, but I have a lot of other mods too. Headers are next.