Mase did a really great job tuning my NA S2000 with PWJDM intake, Toda header, and Berk 3" exhaust with HFC. The exhaust is a very nice piece but it's also very loud for a DD / weekend warrior so I've been considering throwing on a milder exhaust. If I opt to run a more restrictive exhaust, will that require a retune or would it be pretty safe? I've read a lot of threads about how going from stock to aftermarket exhausts usually require a tune, but I'm wondering how much the freer flowing exhaust deviate from one another - are they all in the same ballpark and should be safe on my engine? Mase is down in FL and I'd rather not go to a local tuner if I can help it.

 

You won't damage anything by not getting it retuned, but you will definitely change the shape of your torque curve by swapping out the Berk with an exhaust that has a conventional HFC and exhaust with a resonator in the OEM location. Resonators cause very significant resonant humps and dips in the VE and torque curves, so if you don't get a retune, your AFR curve will have rich and lean places that didn't exist before.

I don't want to sound too much like a salesman, but I encourage you to look at my midpipe thread, since I think the best solution for you would be to replace the front part of your Berk with my mid-pipe. I haven't actually tested my midpipe with a Berk single, but I believe you would increase performance while reducing drone.

 

Gernby! How much work would it take to mate your pipe to a CT exhaust?

 

I'm not familiar with that exhaust, but I don't think it would be much different than any other exhaust. BTW, this is pretty off topic!

 

This isn't QUITE the same, but when I swapped from a comptech header back to the stock header, I really had to go in and change my fuel maps in the midrange. From ~4-6k rpms the fuel curve went from looking like two mountains to a small hill. The comptech header has a lot of resonance points compared to the stock header on an N/A motor, that definitely warranted a retune.

If you plan on changing from say a Berk single to something like the Invidia Q300 single, there probably wouldn't be much change, but if you went from your single exhaust to a dual exhaust, like gernby said theres gonna be a lot of rich / lean spikes in places that there weren't before.

If you have a wideband, you can just swap it out, and look at your AFRs at WOT and determine for yourself if it's worth retuning or not.

 

The good thing about your car being a DBW model is it has the closed loop lambda control all the time. The o2 sensor should adjust short term fuel trims.

but any event, if you can datalog it and email it over, I will fix the fuel map if it changes.


To answer the question will it change the needed pulsewidth, it honestly depends, Id say 50/50. Headers and Intake changes usually will result to changes in the calibration more often than cat back exhausts.

Matt lets talk more in private about it.

 

The '06+ models don't have closed loop lambda control all the time unless you set the target lambda adjustment tables to a value higher than 12.49. If you do set that value higher than 12.49, then the ECU will apply fuel trims to maintain whatever value you set. However, most '06+ models have a primary O2 sensor that reads much richer than it really is, so if you target 13.0, the ECU will actively target something that is closer to 14.0.

 

not always, Ive tuned probably more than 30 s2000s on flash pro. Its vital to reference w an accurate wideband.

 

I agree that the O2 doesn't always read richer, but I've only found 1 that is accurate (mine). Every other '06+ that I've tuned (lots of them) have read richer than actual. Basically, it's not safe to let the ECU stay in closed loop at full load.