Perhaps Another "Dumb" Question

[RKS.PA]

I've blocked off the heat risers on my 59AB and love the "rapping" sound out the tail pipes. I have Red's Headers and Smithy mufflers.

Does blocking the heat risers also cause a chugging type sound under load...almost like an exhaust leak.

I've checked for leaks and can't find anything abnormal in the exhaust plumbing.

Has anyone else experienced this or do I need to dig deeper??