Car not feeling the same...

Weather can have some effect, but I bet a good bit of it is just you getting used to the power. I feel the same way about my car sometimes, but it's all in my head
Dan

I also have an auto with bolt ons and I would say the weather has everything to do with it. In December the car hits 2nd gear and goes sideways and in May I get not too much more than a chirp on a good day. It ran a 13.1 in the winter and a 13.39 in the spring so again I blame the outside temp and humidity.

Have you ever considered there may be a problem with the CATS? Does the exhaust smell like sulfur at all? My car was doing this when I had the factory h-pipe installed and I too felt like I was loosing power or the power just wasn't like it use to be. I just went with an O/R H-pipe and resonators and wha-la, the car felt more powerful (but it should because the O/R Pipe should add 8 - 10 HP). But, there is a lot of truth to the point that you are getting use to your car and there may be nothing wrong at all. Or it could be relative to the weather. Cool morning air produces more HP. Well it may not produce that much more HP but it sure feels like it does!