I have an STI 4, decatted, HKS EVC running 1.0 boost but otherwise I believe its standard.
The tail pipe used to be a dark black colour on the inside which I believe is normal.
I noticed last week that it is now light Brown & I am wondering what this indicates
I run the car 100% on Optimax & started adding NF Octane booster about 10 Tanks ago, I dont measure it exactly, I put in approx 1/3 of a bottle to each fill.
Is it just the addition of the Octane booster causing this.
I drove from Winchester to Liverpool at the weekend & did several short runs yesterday & the colour did not significantly differ & the performance seemed the same.
Any constructive advice would be appreciated

Thanks

Stuart

 

The NF will turn it with a tint of brown, that is completly normal for Running the NF Race formula.

Nothing to worry about.

 

THANKS

STUART