Hi Guys,

I have a 2002 FD and have spent the last 3hrs searching and reading exhaust posts.

Can someone tell me plain and simple will a cat back exhaust cause over boost, boost creep or any other possible engine damage with out changing the stock ecu or induction system?


all im really asking is can I install a cat back with out any issues?

 

Yes, you can replace the catback without problems. You'll run into issue when removing the main catalytic converter. As long as you keep the main catalytic converter in place, you can change out the catback to whatever you like.

 

One of the problems that I've had over the last 6 months is that often I don't have some of the basics down to be able to understand the posts that I find from searching. BTW, I did find a couple of great glossaries in the archived threads and FAQs that helped a lot. So, if the following is too basic, I apologize. "Basic" is often more than I can handle.

Keep the catalytic converter and change anything you want from it back and you will be fine. As you probably know by now, when you see references to midpipes, it is what folks have used to completely replace their cat. In that situation you may run into problems since the cat acts a significant exhaust flow restricter and without it you can get overboost and boost creep.

Another thing that I've consistently read here, is that with the stock ECU, you should be able to safely change out the catback (again, everything behind the catalytic converter), and the intake.

 

What about something like Bonez high-flow cat? Does it have enough restriction? My car seem to be running fine

 

It did for me. I never had any issues running the following setup:

Bonez Downpipe
Bonez Hi-flo cat
Greddy Power Extreme Catback
HKS Super Mega Flow Intake

on the stock ECU. I ran that setup for about a year before picking up a Pettit ECU.

 

The basic concept is that it comes down to boost control. You should already have a boost gauge, so you should know if a modification makes your boost go up. "Flow mods" are the ones that count - intake, intercooler, y-pipe, and any exhaust part.

That said, the stock ECU and boost control system usually keep boost the same until you add about the 3rd flow mod, not including the main cat. (Removing the main cat is like 2 or 3 of the other flow mods). Mahjik was ok with 4 mods. I got 3 before my boost went up from 10 to 11psi - cat-back, downpipe, and efini y-pipe.

In most cases, if your boost goes up after that 3rd or 4th mod there is no need to panic. You can install some kind of boost controller (manual or electronic) and dial it back down to 10psi.

Just remember when adding a mod to always watch the boost gauge closely before and after to make sure you're not running more boost than the car is ready for. It's probably a good idea to put in a fresh tank of the best high-octane gas you can get just for a little safety's sake.

Dave