get another lid* , save this one in case you change your mind , or sell it to someone wanting one w/ spoiler...
*good used or new repro

of course the spoiler does help at high speeds , = over 90 or so...
I have both front and rear Camaro spoilers on mine, I could really tell that the front 'snowplow' helps above 90 after I installed it, the rear was on it when I bought the car...I first thought of removing it , but the looks grew on me, esp. when it was 'useful'......

Its a very nice clean look w/o the spoilers , and if you dont drive fast and/or want an original look , get rid of it.