While it's not speed related, this section even houses the Cargohold Optimization rig, which increases your ship's cargo hold volume by 15%, a whopping bonus to any hauler. An interesting side-effect is that installing a full set of Tech II or local hull cargo expanders and a single cargohold optimization rig on a Dreadnought, pushes its capacity to well over 50,000, allowing it to hold a repackaged Battleship in its hold.

PROBE RIGS
While there is only one rig which actually affects scan probes, it's useful and peculiar enough to warrant its own mention. The Tech I Gravity Capacitor Upgrade rig decreases scan time by 10% at the cost of 200 calibration and one rig slot, while the Tech II variant is 300 calibration for a 15% bonus. This is important because the covert ops Frigate, which is the game's designated scanner ship, is prevented from actually using two of the Tech II version of this rig. Being a Tech II ship, it has only two rig slots and, if fitted with a Tech II scan probe rig, would be unable to fit either another Tech II or Tech I version. It can, however, fit two Tech I scan probe rigs for a total bonus of 21%. Note that it's not 20%. This is because the rigs are not added together Eve Isk into one bonus but rather applied separately as modules do, so their bonuses are multiplied rather than added together. At this time there exists no real use for the Tech II scan probe rig, unless you are using it on a ship which requires another rig too, such as a covert ops Frigate with the 50 calibration recloaking timer rig. If you are maxing out a ship for scan time, stick with the Tech I rigs.

CAPACITOR RIGS
Time and again, I find people miscalculating the effect of capacitor modules on their ship setups and tanks. The reason is that most people assume that a 15% capacitor recharger increases the capacitor per second their ship generates by 15%. In fact, it increases it by a little more, the same going for the recharge rig. Capacitor generation at peak (33% capacitor) is measured roughly as follows:

((Capacitor amount/recharge time)*2.4) capacitor per second

When you increase the recharge rate by 15%, you're multiplying the recharge time by a factor of 0.85, which is 1.0 minus 0.15 (15% in decimal form).

With the same amount of capacitor and 85% of the normal recharge time, in effect we end up with a capacitor per second generation increase of 17.6%. The 15% capacitor amount rig, however, would be calculated as 15% more capacitor and the normal recharge time, so that rig actually does increase the capacitor per second generated by your ship by 15%. This means that the capacitor recharge rig is about 2.6% better than capacitor amount, but is it always better?

There are ships which would benefit more from capacitor amount than recharge, specifically capital ships. With the common method of killing a capital ship being the neutralisation of their capacitor, more capacitor will literally slow down the enemy much longer than 2.6% faster peak regeneration. Also keep in mind that you will be recharging much less until you reach 33% capacitor for optimal recharge.

In effect, more capacitor gives any setup more resistance to Nosferatu and neutralisers as they reduce the percentage of your capacitor that can be stolen or destroyed per unit time. This may also make it ideal on Battleships in place of cap recharge rigs. Three Tech I capacitor amount rigs will only generate 52% more capacitor per second, compared to 63% with the capacitor recharge rigs. When you have three of them fitted, those 2.6 percentages really start to make a lot of difference.

RIG DRAWBACKS
Most rigs come with a built-in drawback to balance them out. The drawback depends entirely on what class of rig it is. These drawbacks can be mitigated by 10% per level of the appropriate skills (Shield Rigging skill for shield rigs, for example).