So I just took out a magnaflow hi flow cat and installed a bonez midpipe. It was fine all day in the heat but at night I was overboosting hard and hitting fuel cut (at 4500rpm+ the tach would bounce up and down and not want to move)

what should I do to address this? My car was recently tuned but here is my set up

bnr s3 with Mac valves
adaptronic select
supra fuel pump and larger injectors
aquamist water injection
hks downpipe
racing beat catback

it was tuned to be limited at 15psi, but my boost quickly spikes up to 19psi and hits fuel cut. I did this a few times to make sure, hopefully didn't damage anything but the motor still seems to run fine.
thanks!

 

Tuned before or after installing the midpipe? If before, get it retuned - it sounds like you have all the supporting mods in place.

 

If it's creep, reinstall the cat.

 

Could also port the wastegate, not sure how much meat is left on the BNR's, though? Other option is to fit a restriction plate in the exhaust .

 

put the cat back in.

 

Your boost controller may not be compensating for the additional flow. Try turning the boost control totally off and see what your boost looks like, if it's low all the time you should have enough waste gate to handle the job. At that point you would just need to re-program the boost control to get boost back to where it should be.

Dale

 

this^