Honestly a colder tstat will help and should be done in conjunction with the 104s as it will help keep the motor a little cooler which helps the continuous kr battle. That and a tstat is only a few bucks from Autozone. And running no cat isn't mandatory but as well it helps to not run one. Trust me I speak from experience. What I posted will help him get the most out of his 3.5 without going cam intercooler or rockers