Which catalytic converters

Hello,

Very nice choice in rides. I myself own a 1997 Mustang GT supercharged with a Vortech V1 supercharger producing about 12lbs. Of boost at 5500 RPM's. I have owned the car since I got it, straight cash deal, and I live in a county in California that doesn't require annual or bi-annual smog checks, only when the vehicle is sold or purchased, so I have completely gutted my catalytic converters, all 6 of them, and am running straight pipes. Although, I am thinking of getting a pair of high flow catalytic converters, mainly for the people behind me in the drive through line. ;)). High flow catalytic converters will definitely let your vehicle pass smog, and although there is a lot of talk about engines, like our 4.6L's, needing back pressure; I don't buy it. Let's face it, an engine is really nothing more than an air pump. Yes, it does take gasoline to make them run, but they do not run on gasoline. This is an important concept that most people don't comprehend. The optimum air:fuel ratio is 14.7 parts air to 1 part fuel, so there is much more air needed then fuel. To make horsepower it's as simple as air in and air out. Back pressure can, by it's nature, only be resistant to that. Anything that American Muscle sells, take it to the bank. Is the highest quality aftermarket part for your Mustang available today. Period. Do not have a second thought about the quality or the effectiveness of the part. Now as far as your hiccup, I don't think that it is back pressure related, because if it was a mechanical related it wouldn't just happen in first gear, it would happen whenever the engine RPM's got to where the hiccup was occurring, regardless of gear. What exactly is your vehicle doing in first gear? Also, is your vehicle's Malfunction Indicator Lamp [MIL], or "check engine" lamp illuminated?

Thanks,
Alex
2CarPros

What are the Direct Trouble Codes[DTC][s] that you pulled from your vehicle? Here is a link below explaining how to pull them with a code reader:

https://www.2carpros.com/articles/checking-a-service-engine-soon-or-check-engine-light-on-or-flashing

Please get back to us with what the codes are and we will have specific instructions for you on how to fix it.

Thanks,
Alex
2CarPros

Hello again,

These two DTC's are DTC's for both of your vehicle's catalytic converters being worn out. P0420 is for bank 1 and P0430 is for bank 2. Here is a generic guide for changing catalytic converters below:

https://www.2carpros.com/articles/catalytic-converter-replacement

In the diagrams down below I have included a guide from the vehicle manufacturer for the replacement of the catalytic converters specific to your vehicle. This, however, probably isn't going to relate to the problem with 1st gear hesitation unless they are plugged, but that would cause loss of power, period, and engine overheating. Is there any way that you could take a short video of whats going on when you take off in 1st gear for us and upload it so we can see exactly whats going on?

Thanks,
Alex
2CarPros