Handheld modifiers vs in-line

[schreck]

I love my Yaris but let's be realistic -- the mid range grunt just isn't there.

I've seen this various EBay based ads claiming in line performance chips will add 50 hp but I know these are usually nothing but somewhat dangerous modifiers that confuse the ECU into thinking the engine has more hp than it really does.

I've also seen TV tests of handheld programmers such as the Bully Dog, but these are usually for trucks and diesels. These can be safer since they have limitations; however, does such a handheld programmer exist for the Yaris?

If anybody knows of a safe in line chip, I'll listen to recommendations on those too!

Thanks