well, it will NOT make the car go faster...but the spoilers will make it better handling , especially the front "snowplow"...will push your front tires to the ground at higher speeds...you will feel the difference if at 80 mph or faster....only the rear spoiler will make the car handle less..it will push rear down = front up...
and you CAN add your 400 emblem to the rear of the rear spoiler (I did)...yes ,its a Camaro part added to your Firebird...but it is 'performance' enhancing....IF you like the better handling...just as wider tires etc will enhance the original design...IF you only drive slow or only take it to shows to have an "original" car..do NOT add these...

IF you do add them , do it as a set, front AND rear...or only do front....only rear is not good!