As stated in Arsenal you are allowed to remove standard upgrades from vehicles and weapons. crazyconscript and InfinityzeN however posted here that you do not get any benefits from doing so. In my opinion this is not RAW. And I do not think it is the intention of the rules either. If you remove as smartlink from a gun or armor from a car there should be more room than with the upgrade.

As a sidenote, am I missing something or are there no rules in SR4 to create items (vehicles and weapons in particular) from scratch?

Okay, here is how I deal with the issue. Factory included mods do NOT count against the normal maximum number of mods that a gun can have (six, in most cases.) However, you CAN remove them with sufficient time and money. However, you do not gain additional mod slots from doing so. (In other words, if you remove the smartgun system from an Ares predator, your predator does not gain an additional slot for modding.)

So, why remove factory mods?

The FN HAL comes with a gas vent 2 system, which is nice, but most runners will want a gas vent 3 system. So you can remove the old system in order to put a new one into place (though doing this would probably require a facility.) The Browning Ultra power comes with an over-barrel laser sight. If you need that area for, say, a vision scope, then you can remove the laser sight in favor of putting a pistol scope on it.

Lastly, I am not aware of any rules for making your own vehicle/gun. I know that they were in SR3, but they seemed to do away with it in SR4. Probably just as well, those rules were REALLY convoluted, hard to follow, and they were almost never used. Our group continuously pipe-dreamed about what we could do, but the end product was so crazy expensive that it never worked out. Only time it ever happened is when my adept spent his ENTIRE campaign pursuing the creation of his own pistols, which he never got to use until the last run.

There are not "Create from scratch" rules in SR4. That's rather sad too. One of my players in SR3, a pistol PhysAd, started with a pair that he made from scratch himself.

And hopefully I didn't come across as an ass in the other thread. I actually agree with you on a lot of things. Cheers.