I've noticed lately that my car has been lagging just a little bit on the power when I get on it a little bit. I have no mods, except for exhaust. It seemed before like maybe the vtec would engage for something to add a little burst at maybe around 3500 or so (I'm not sure), but lately I haven't been feeling anything like that. It's not a big deal, but I'm just curious more than anything what may cause something like that?