Hey Vinnie,
two things that people might find useful when using this update set. According to Spielberger's "Sturmgeschultz * It's Varients", the smoke grenade launchers were only fitted to StuG's from February-May 1943. It was reported by troops in the field that enemy small arms fire could pierce the tubes and set off the smoke grenades. So only vehicles built during this time frame should have them included.
The armoured shield you refer to, i beleive, was to protect the exhausts. Agai nthis is a feature that was only used on certain versions of the StuG. For instance those StuG's built on the Pz III M chassis did not include this feature if they had the deep fording echaust system. From what i can find out this armoured shield was not included on that many versions of the StuG and it seems to have been a haphazard implemntation that started around the time of the introduction of the F/8, so check your references before adding this shield.
Regards from the Swamp
Eth