Raptor Headers, Aftermarket Cats and O2 Sensors

[Curley5959]

I have some questions in regards to upgrading my exhaust, and the effects this may have on fuel economy, performance, and noise.

Car is a 2004 Liberty 3.0R Spec B currently tuned by Matt from KiDo.

At the moment, I have a 2.5" cat back exhaust system, with resonator delete and Ultrex Performance Mufflers. A set of Raptor Headers are on their way slowly, and I starting to work out what I am going to do.

Current Setup - Stock Headers to Stock Dual Cats to Stock Single Cat to Flex Joint . From here it goes to 2.5" pipe to Hotdog Resonator then branches off to Ultrex Mufflers.

Proposed Setup - Raptor Headers to Dual 300cel Cats (Remove Rear O2 sensors and switch off in tune to remove CEL) to 2.5" pipe to Flex Joint to existing (ie. 2.5" pipe to Hotdog Resonator to Ultrex Mufflers).

One question I have is are there any benefits to going with aftermarket cats and having everything repiped? This would involve purchasing cats, and depending on which ones having to get O2 sensor bungs welded in and piping it through to the existing setup.

Are there any side effects of removing the rear cat, updating to hi-flow cats and repiping through to my existing setup? I have been advised that I would need to turn off the rear O2 sensors when running hi-flow cats. Any side effects of this? Would fuel economy suffer (I get around 9-10L/100 on my current setup)?

After having the headers and exhaust done, I would be seeking Matt's help for a retune.

Any advise would be appreciated.

Thanks,
Aaron