How to tell if all 4 barrels open- 4 speed car

Not downshifting. Just cruising along in fourth gear, then punch it. When I do this, the car will pick up a lot of speed, but no kick like you get with an automatic. I guess it really is due to the automatic downshifting when you nail it. Just trying to make sure I'm not missing anything. It would be a bummer to find out a couple of years down the road that I've been driving on only two barrels!