I was having misfires when Cobb was on. Walnut blasting and replaced plugs at the same time fixed it. Don't know/care which part fixed it it runs much, much better now.
'07 335i E90 | Cobb Stage I
'03 Porsche Boxster
'07 Alfa Romeo GT 2.0 (sold) // '06 325i E90 (stolen) // '99 Alfa Romeo 156 (sold)