My cap has been in the trunk for the last couple of weeks and I feel there is an improvement in mid-range pull. I had THF installed for about 6-8 months and discovered the extra pull by accident when I forgot to tighten the clamp and the hose fell off. One morning my idle got very rough and was hunting-stalling, but the car was pulling like crazy when I stepped on it.
When I got to work I popped the hood and noticed the hose had come loose. With an ATX this wasn't that useful anyway. I just let it warm up for an extra 10-15 sec. now.
