WARNING: The Retard Eliminator effectively eliminates any retard who thinks they can hop on a TL and give it any kind of throttle in a parking lot. It immediately eliminates the retard by planting them head first into the pavement.

All kidding aside, TRE is by far the best/ cheapest mod there is. Just make sure you get one that works or make your own.

about the TRE:

TRE stands for Timing Retard Eliminator. Suzuki made a big effort to make bikes safe for consumers so they put restrictive devices such as flapper valves (search for the joe-v airbox mod on tlzone.net) and retarding the timing to make the bike less likely to jump out from under you when you hit the gas accidentally in the first couple gears.

Suzuki designed the bike to stumble or have degraded performance in the first 3 gears to make the bike a little less nuts by retarding the timing in those gears. The TRE overrides this by telling the bike it is in 5th or 6th gear when when it is not.
 

Answers to FAQ:
1) TRE is Timing Retard Eliminator which eliminates the factory decrease in performance of the first few gears by telling the ECU the bike is in 6th gear
2) PCII or other mapping devices (Yosh, Teka) do not do what the TRE does and they can be used together
3) The TRE should not hurt your bike BUT if the TRE is not the active or transistor kind then starting or idling in neutral may be difficult
4) 80% say they feel a difference -better response, 10% say they feel a big difference and the bike runs much better, 10% say no differance.
 

I built mine based on Steve's design http://wotid.com/tls/content/category/1/27/57/  I have copied Steve's info here in case his stuff should somehow disappear -please follow the link to Steve's site.

Testing

Testing that the unit is working is pretty straight forward. Use a high impedance digital multimeter set on volts DC. On the Pink / Red wire that goes to the ECU you should get the following readings down to ground.

In neutral, close to 5.08VDC

In all gears using a 15K resistor, close to 4.70VDC

In all gears using a 6.8K resistor, close to 4.38VDC

Make sure you test the circuit -if the circuit is open the ECU reverts to a neutral map = yuck!

*Update 06/09

Advanced selectable TRE

With a TRE your ECU is tricked into thinking that your bike is in one of the last 3 gears that are not retarded (TLs come retarded for safety) This is done with a TRE. The TRE is a false GPI or Gear Position Indicator.

With this particular flavor of TRE you are able to select which gear you want 4,5,or 6. That means you could map gears with a "Power Commander" for 4,5,6 individually and change them on the fly. For example the map for gear 4 could be a commuter map. Map for gear 5 could be a torque map for 2 riders, and gear 6 map could be a race map. Each map will apply across all gear except neutral.

So as shown below

Switch Position 1) OFF -TRE override
Switch Position 2) 4th gear map
Switch Position 3) 5th gear map
Switch Position 4) 6th gear map

A 6 position switch is shown with positions 5 & 6 on the switch not connected