Excessive heat from exhaust?

I recently installed the Bosal stainless cat-back exhaust on my truck (5VZ-FE). It's a little tight fit around the OME Dakar leaf springs with AAL, but it fits well enough.

I just noticed that the chrome exhaust tip has started to turn blue. I'm trying to figure out what causes this amount of heat. I've checked my air fuel ratio and it's pretty consistent at 14.7. I'm not sure what else would cause this.

What do ya'll think is happening? Or, is this normal?

 

Stainless steel will always turn those colors from oil from your hands touching it during install . You can remove this discoloration by scuffing down the pipes with a red or green scotchbrite pads . Then applying a good rubbing compound on the pipe to keep it looking good

 

In the Ricer World…..that’s exactly what you want to see
That iridescent/rainbow color

BTW
Guys pay alot of $$ to get that hue/shade/color

 

I would use something softer than a scotchbrite. I did that on mine and it scuffed it up more than I anticipated.
OP color looks normal

 

Normal