s2000maniac

Right now I got a K&N intake, PLM header, invidia 70mm test pipe, and invidia q300 exhaust. I just got a apexi vafcII and will be doing a tune pretty soon. The exhaust has become a lil too raspy for me after the test pipe install. If get the tune and then eventually replace the test pipe with a Berk 70mm HFC, would I need a retune?

S2k-2NV

You should be fine without re-tuning the car after switching from a 70mm test pipe to a 70mm HFC. I was in the same boat as you, the Q300 along with an invidia 60mm test pipe was too raspy for me but then i switched over to the berks 63mm HFC and the car ran just fine. I really did not feel any difference in power loss and if there was any loss it would be like 1hp or less.

deepbluejh

Agreed. The difference is going to be very small. I definitely wouldn't pay for a retune. At worse, you're going to run a tad rich, but that's safe and it will leave you a little bit of extra headroom for mods in the future.

I say leave the tune alone.