Hemi 5.7 Exhaust System

Hi all, I am installing a 2010 Hemi 5.7L crate motor in my 1974 Australian Valiant Charger. The motor has come complete with wiring harness and I have purchased the March Performance serpentine kit with A/C pump, Alternator and power steering pump.

I am now looking at the exhaust system and I was hoping you guys could answer a few questions. I am planning to keep the engine internally standard, but I wanted to install a performance chip and an appropriate exhaust system. The engine has the standard shorty headers at the moment, but I am considering a set of extractors. I will be running the Control Freak front suspension so I am unsure of clearance issues. My questions are as follows:

1. What is the best chip available for the engine
2. What diameter exhaust should I run for best all round performance
3. Should I change the headers for extractors
4. How many exhaust gas sensors does the engine run, 1 or 2

Thanks in advance
Jacko:toothy5: