Alot of guys have done it on here I'm sure they will chime in. I considered doing it but after doing some research I figured the Toyota engineers had a reason for doing the "D" shaped one, so I left it.
ive got it, i dont think it did anything, but id have to agree with the toyota engineers comment above. Its like that for a reason unless your supercharged. Im pretty sure this mod gave my truck a funky idle, I took it in a while ago and the tecs said it was ok. so i guess there is no harm doing it