Recently went catless on my gen 2 is250. I know there are plenty of plug-in tunes, just curious if anyone has done a diy tune on one. Having a hard time finding the bin or the definitions, pretty new to this.

 

VFTuner just started supporting the 4GR-FSE powerplant in February, and AFAIK, they are the only DIY tuning solution. After playing around in their software a bit, it's fairly straightforward what you can and cannot do, and if you understand the basics of using fuel, air, spark, and timing to produce more power, you should be able to clean up the factory tune a decent amount without a dyno, though something like a dragy unit would still be better than reading the MAF flow and AFR numbers while relying on the denim dyno.

 

How much HP could you gain with that tune?

 

I'd assume roughly the same as the aftermarket flashes would give you, except you'd know what aspects of the tune were changed from factory settings and by how much, instead of bragging about throwing money at a company.

More for the "Built Not Bought" crowd, if you will.

 

Maybe 15-20hp if you really know what you're doing.