i always thought a sniffer on a catless exhaust was very accurate. i just had a tune running around 23 deg of advance on top and 11.5/1 and my egts are running high. my local suby people think it may be due to the fast that im running an EWG and thats throwing off AFR readings. i dont see how that could be so since the readings are a sample of the mixture, i wouldnt think the volume would matter. any opinions?

Add some timing? Fuel burning after combustion chamber? How hot is EGT? I'd get EGT down to norm and ignore the A/F. Sounds plenty rich to me??

Sometimes, a tailpipe sniffer can be 'wrong' if not used properly or there is a leak----as can a screwed in, bung type if there is a leak at an exhaust joint near it.

That could account for a bit of an AF descrepancy.

well when it was getting tuned it didnt really like any extra timing. 2 deg was added and it was getting knock on the top end around 6K