As of now, I have a K&N replacement air filter, an HKS dp, soon to have a Racingbeat cat-back, and debating on gutting the cat. How much of a risk would I be taking by having these mods and running the stock CPU for right now? I do plan to upgrade in the future.

 

ECU..
CPU sits on your desk

 

Excuse me for being unpolitically-incorrect

 

Don't you just love it when someone takes the time to respond and provides no positive input. Don't let it get to you..

To your question, I would not do it. With the DP, catback, and K&N I personally think it is not worth the risk on the stock CPU. And while gutting the cat will increase your exhaust flow you will be risking running lean at high rpm or overboosting, you will also be ruining a perfectly fine cat (assuming it is). Save your money for an ECU and then buy a midpipe, they aren't too expensive and will give better flow to boot.

 

High risk. Free flowing exhaust means boost spikes and creep, although if you're using the completely stock intake setup (even with K&N filter), at least one end is partially choked off. Still, you're rolling some rigged dice...

 

ive been running the mods in my sig on the stock ECU for many months now....havent had a single problem

-Zach

 

I've been running the exact same set up, 3" dp, gutted main cat and greddy cat back with k&n replacement filter for over a year. I DO HAVE a Profec B so I'am sure this is helping me keep it at stock boost levels. What are you boosting right now? Mine does not spike or creep at all. It's a rock steady 10-8-10 and on very cold nights which is rare here in Texas, it gets 11-9-11 boost pattern. I would not open up my intake any farther with out an upgraded chip or standalone. As long as you are at 10 psi you could put every single bolt on you would like, just keep it at 10 psi.

 

whoops.

 

whoops.

 

I figured you would get differing replies on this, which is a positive thing. Something to keep in mind though is that not all cars, especially RX-7's, repond the same to matching mods.. one car may run fine with xxx mods but the next one pops the motor the first week out. A better way to look at it is this, is it worth a $3000-5000 risk to you for an extra 20HP?

 

Keep the boost down to 10 psi until you can get an ECU

 

I ran a DP, K&N, Random HFC and Apexi duals for about a year with no problems. I was a little nervous though. I was running a manual boost controller on the wastegate and precontrol though, at about 11#'s of boost. Here's a pic of the needle valves I used.



Mcmaster.com has em'. Very nice. They have color coded disc on the shaft, as well as numbers on the ****, plus a set screw to lock it all in place. About $15 each.

Regards,
Frank

 

At the very least get a decent boost controller to keep the boost creep away. I personally wouldn't risk it tho even tho others have gotten by. Just my .02.

 

wow, thats a nice looking homemade boost controller. looks much nicer than the basic "home depot racing" valves, much more professional looking. still has that plumbing look to it kinda, but it is much more presentable, in my opinion. good job, buddy.

 

So if I can keep the boost to normal levels (under 10 psi), I should be ok? The only reason I was debating on gutting the cat was because I think it might be partially clogged. How can I check to see if it is?

 

If you take it off, turn it on its end, and chunks of converter brick and metal webbing come out, it's toast.