[601HP]

After several years I changed from 1x4 to 2x4's (600 cfm vacuum secondaries). The power increase was surprising, but I expect the majority of that increase was due to the dual S&H air cleaners as Naumoff stated.

I did some minor tuning/tweaking that wasn't difficult. I found it interesting. The 2x4 setup is quite smooth for me.

The wow factor appeals to me. My wife misses the turkey pan.

David