I was dyno'd already w/ JWT pop, z tube, 5/16th spacer and megan test pipes. Got a car inspection coming up soon and instead of swapping the stock cats back in i was thinking of switching to Berk HFCs how bad would my car run with HFCs since it's tuned for Test Pipes? I'd get it re-tuned whenever i decide to buy exhaust...

 

Shouldnt be a big diff from going to no filters to a 200cel filter (Berks) or is it 150cel.. cant exactly remember. You should be okay but it is recommended that you get a tune and I'm sure a lot of other members will say so as well.

Wait till you get your exhaust and Berks all together then get a tune.