From 
1998 - 
2000 there was a sub-category
 of the Technic theme called Competition.  Unlike traditional 
Technic sets which are typically scale models of a real vehicle with 
carefully reproduced functions, these models were not based on any 
real-world subject and are intended purely for competitive play.  
In general, the sets each came with two models which were intended to 
battle each other.  The factions were identified by color.  
The new turquoise color represented the humans, and the purple color 
represented the cyborgs or human/robot hybrids.  Most of these sets
 came with Technic figures.  The cyborg figures featured new heads 
and arms with simulated mechanical detail.  In most cases the 
functions involved some sort of articulated striking mechanism which 
could be actuated by the user and then retracted with rubber 
bands.  This striker would be used to try to impact the target of 
the other model.  A successful hit resulted in the pilot of the 
impacted vehicle being ejected or some other form of spring loaded 
destruction.  In many cases the two models were nearly identical 
except for color, making for an even match.  However in other cases
 there was a clear distinction between the hunter and the robotic 
target.
Apart from the new colors unique to this theme, this theme also 
introduced the competition cannon.  This system involved a launcher
 and a rubber tipped projectile.  In some cases, the projectile was
 used as the striker at the end of a mechanism rather than being 
launched.  Many models used shock absorbers to spring load 
functions.  Other models use either rubber bands or bungee cords to
 store energy.
The colors are rare enough that they are of limited use in other models,
 but these sets came with large numbers of uncommon thin liftarms as 
well as a wide assortment of black Technic parts.
Sets 
8305 and 
8307 don't
 really fit the category very well, but they don't fit anywhere else 
either so are included here.  They are still competition based play
 sets but with a different theme.  The 
Bungee Blasters are actually from 
1997
 and not officially part of the Competition theme, but they fit in very 
well with the Bungee Choppers and the competition concept in general.
On a personal note, I always thought that these sets did fit in very 
well with the Technic theme.  However, they are among the favorite 
models of my entire collection for my younger children, so LEGO
® was successful in expanding the line to a younger audience.