EdwardNorth

Hey all,

I searched but didn't find a definitive answer about this. I currently have an M2 downpipe and a custom-fab mufferless catback on my FD. I will be replacing the catback with a RB dual-tip, and I was wondering if it would be safe to also upgrade my stock cat to a Bonez Hi-flow considering that I'm running off of the stock ECU.

I have no other performance mods (although I do have a K&N filter in the stock airbox, I doubt that does much of anything for performance). Will I be safe or will I run lean and/or get boost spikes?

Thanks guys!

Nameless

Experiences seem to differ from person to person. I used to have an M2 CAI, M2 DP, Bonez Hi-flo, and an Apexi dual on a stock ECU. It kept going til the coolant seals let go (which wasnt due to the mods).

My boost went up to ~12 lbs with the setup mentioned above.

DaedelGT

If you can keep the boost to 10psi you can run the stock computer. Get a boost controller, and you may have to port the wastegate.

EdwardNorth

I plan on getting a PFC this summer anyway, so if there's a good chance that the boost will get out of control I just will hold off on the hi-flow until then. If people have indeed ran a full exhaust w/hi-flow cat as their only mods safely, then I will probably get the hi-flow at the same time as I get the RB catback and install them both together.

Thanks for the replies!

tt2323

boost controller for sure..but they can be had cheap, with just an exhaust, or just a downpipe i was spiking to 12psi

rynberg

As far as searching goes, there have been at least five threads regarding this topic in the last two weeks alone....

As long as you stay at 10 psi, you will be fine. Now, you may still have acceptable boost after installing the downpipe and cat-back, but you may not, so be prepared to buy a boost controller (manual or electronic). With the hi-flow cat, you will definitely need a boost controller to maintain 10 psi, but porting the wastegate will not be necessary.

EdwardNorth

Well, I did a title search for "*flow*" and while that pretty much turned up all of the hi-flow cat titles in existance, I didn't notice anything that specifically referenced the topic of DP, CB, and Hi-flow on a stock ECU. I opened quite a few of the threads that I thought might say something, too. Plenty of Intake w/DP and CB questions out there, and even Midpipe questions, but nothing specifically addressing my question.

rynberg

Here's the results of searching using the terms "mods stock ecu".

https://www.rx7club.com/search.php?s...der=descending

You'll notice that there's nearly twenty threads in Feb alone and almost 800 total.

I'm not really busting your *****, I think it's great you searched first. You just need to try a few different terms for searching, that's all.

EdwardNorth

Cool.