Ok guys, new to the Evo and turbo cars. I had a supercharged FR-S that I tracked a bunch but really liked the Evo X so I changed vehicles and am learning this platform.

I recently did all the standard bolt ons and took it for a tune. After the car was tuned I was told that tracking the car with a high flow cat isn't as safe for the motor as running a test pipe. I usually run 5 or 6 sessions at 20 to 30 minutes each with an hour or so between them.

So my question to those of you who beat the hell out of their car on the track, should I take heed and ditch the high flow cat and pick up a test pipe and retune? I don't want to drop the $ unless this is a known fact as that is basically the cost of 2 track days .

 

The choice between a high flow cat and test pipe have nothing to do with the safety of your motor. People run stock cats at the race track for hours with no issues. If they are worried that the added back pressure caused by a HFC versus a test pipe could be dangerous, they are wrong as well. The fact that your were tuned with a HFC means your fuel and timing maps were adjusted with that in mind. Reducing back pressure is a good way to pick up more power, but you don't need a test pipe for a track day.

So to answer your question, No. Don't install a test pipe and get a retune. It's best to collect several parts, install them at once, and then get a retune.

-pal215

 

Do you drive this car on the street?

 

Thanks @pal215 .

This car serves as my daily with occasional track duty. I wanted to retain the cat in an attempt to not completely **** off my neighbors at 5am everyday when I leave for work. I went in knowing this would net less HP and honestly I'm not really concerned about the extra 10hp. That little difference won't amount to hardly anything if anything at all of reduced lap times. If I ever do more to the car, which I likely will, I can revisit this decision at that time. For now I just wanted to confirm that running with the cat can in no way be harmful to the motor so long as it was tuned with the cat on the car.

 

You are correct that your high flow cat will not harm the motor.

For a street car, you should keep the high flow cat. And if the cat really is high-flow and you're not on some ridiculously large turbo setup in the first place, I'm not even sure that you'll be losing anywhere near 10HP here.

 

Where's the damn thanks button on this forum...

 

FWIW, I had the mil.spec 100cell on my car at 360WHP level. Pulling it off changed the power on the virtual dyno logs exactly...zero. Nodda. No change in fueling (on speed density) to make me think it did increased airflow either.

I have a 200 cell cat on my daily though and it struggles to pass an OBD-I sniff test. I'm not too convinced these high flow cats actually do much "catting." Seems to have trouble getting up to and staying at light off temperature.