I had a stock reflash done to my 05 gsr. Since then I added a high flow cat and drop in k&n filter. I am not going to add a mbc and keep the boost at 21. do i need a reflash again? Thanks war or al.

 

i mean i am going to add a mbc

 

No, not really, but why are you adding a hi-flow cat to a stock exhaust? That will do absolutely nothing - you can spend that $200+ better elsewhere.

 

I was under the impression that a high flow cat will free up the exhaust a small bit. Another quick question, I just installed a boost guage and it says my boost maxes around 21 and tapers off to about 16. I got the flash that supposed to get rid of the boost taper. Does dropping off to 16 sound correct?

 

Nope. the taper won't stop until you install the MBC.

 

What clay said

 

Boost will still taper with a MBC just not as bad. U need a EBC with a stepper motor or a high load WG to eliminate taper.

 

The stock turbo is going to always taper, because it can't flow as much at high rpm, so don't try to eliminate it completely with an EBC. However, reducing taper as much as possible is desirable, so get an MBC.

Yes, a HFC will SLIGHTLY increase flow, but we're talking less than 5whp. It's still a cat, so it's still very restrictive. Plus, you still have to send that exhaust through a restrictive cat-back.