because thats all it needs? in all honesty for reasonable and practical use, you will not find much, if any, difference in the shooting of an ego7 with zick kit fitted and the sl74.
meh, leave it for the techy types. just shoot it and enjoy!! as far as i know, qev's are really only there to increase the peak rate of fire. when the 07 is capable of 32 odd bps an extra qev isn't really necessary.