The answer is yes, if you buy a down pipe for the Fiat 500 Abarth, it will bolt up to a Jeep Renegade equipped with the 1.4L turbo. I went with the ATP 3" down pipe with the high flow CAT. You can see how much bigger the outlet is. Because the outlet is so much bigger, you have to notch out some of the factory support bracket. This is required no matter what car you put this on. The only concern was the O2 sensor bung being in a different spot, but it went in just fine. Here you can see the support bracket and the flange meeting up to the factory exhaust. And here is the view from the top. Initial thoughts: the turbo spools a little faster. There is noticeably less lag when I'm rowing through the gears. If you are in gear and need to accelerate, the response is better as well. No real change in noise level as the rest of the exhaust is still the same. That will be my next step. There are plenty of options for down pipes for the fiat 500 abarth. It would be safe to assume any one would work, but I used this one: https://www.atpturbo.com/mm5/merchant.mvc?Screen=PROD&Store_Code=tp&Product_Code=ATP-FIAT-001
After a few engine cycles, the check engine light came on. The high flow CAT just isn't as efficient as the factory one. Normally I wouldn't care about the light, but the renegade disables four wheel drive mode when the CEL is on. I just ordered a part from amazon that claims to be able to fix the problem. I will keep you posted.
Here is a before and after of the spacer installed on the o2 sensor after the CAT pipe. Mostly bad news though. I installed the spacer adapter, cleared the code and drove it around for a few days. The same code eventually came back. P0420 - Catalyst System Efficiency Below Threshold. I'm still looking for a solution to this, but for now, I just keep clearing the code. The CEL comes back after 3 or 4 engine starts.
Try a spark plug anti fouler or 2 to extend it out a bit further from the stream . You could also try one of the "j" shaped spacers.
I did get the "j" shaped spacer which got the first code to go away. Now I get two different codes: P0139 - O2 Sensor Circuit Slow Response P0141 - Sensor Heater Circuit Logically this makes sense as moving the sensor further from the exhaust gas would cause it to take longer to heat up and/or react to real time changes in exhaust gases. If I clear the codes, I get one good run with no light. The next time a start the car and it reaches operating temperature, the light comes right back. This is a bummer. My next idea is maybe the sensor is bad? I also have looked into nerfing the sensor electronically.
I imagine the problem is not so much that the cat sucks, but that the sensor is just in the wrong place. Sounds like it may be less effort to perhaps heat wrap the stock unit and spend the effort on perhaps going with a nice large single mandrel bent straight pipe to reduce back-pressure there instead.
