OK I scored a new head and a bunch of other stuff for a 89-90 renix. Mine currently is running good. So, what could I do to the other head to make it better when I replace my current head. It's got over 198K. I'm not looking to make a screamer out of it, just more efficient and better. BTW the new head has less than 10K on a rebuild and looks primo. no carbon build up and is the same casting as my current head. Just want a long lasting slight upgrade in performance. Thanks in advance to the most knowledgeble audience. OBTW it is a stock '90 xj 4.0