Inside muffler glowing red normal?
 

I got a 92 rx7 fd. just rebuilt the engine. the car idles fine between 1100-1500rpm and air fuel ratio of 10-1. car has a front mount intercooler, hks rs intake, hks downpipe, racing beat single tip cat back and still has oem cat. boost only hit 8 psi and when diving the air fuel ratio sits between 10-1 and max 13-1 depends on how your driving. car drive fine but my brother was following me home and noticed that inside the racing beat exhaust it was glowing red. the outside piping was still normal color. cat was not red. all outside piping looked normal color bit inside the muffler was cherry red. I don't believe the clutch in the air pump is bad and I don't believe the car has been tuned. I know I need a stand alone and a tune but on the east coast of Canada hard to find a reliable source. like I said tho the car runs and drives great just noticed today that the inside of the pipe was glowing red just wanted to know if anyone else had noticed this before and if its normal or how to solve this issue. any help I would appreciate.
thanks

Dude..I know it has nothing to do with your exhaust but there is a TUNER that is coming your way.
Hit the CDN section..There is a Group TUNE being set up...In Halifax I believe.

thanks will check it out.

timing ..... very retarded .. or running only on trailing ignition

Wouldn't you feel a lack of power or my air fuel ratio be less then 10-1?

Ehh I dunno about that.

If the muffler internals are a thin gauge steel it is very possible for them to turn red under harder driving conditions. If you are confident in your Wideband O2 sensor calibration then I would not worry. Also get a timing light on the engine if you have not before.

ehh.. i do know about that,, been there done that.. if the cat or front muffler glows its eaither blocked or exactly what i have posted IS happening

and since the ignition has less time to burn out the oxygen,, what do YOU think will happen to AFR results???

just same as any other car

they look RICH

It's not the cat or the outside of anything it's just the inside of the muffler when your looking at the baffles. The car runs good too. It isn't missing or anything like take sounds healthy