I've been running an HPI Sport 2 and Pro 2 for many years. I still run them in stock classes. They are great cars. I believe you can still find old setup sheets on HPI's website. If not, I have them all printed out. You can usually still find parts on ebay. I've upgraded a few things on the Sport 2. I think the most important upgrade is install ball diffs. As for lipos, the chassis can take saddle or stick packs. I'm running the reedy 4800 saddle pack lipos in my car. It's a tight fit, but it works well. PM me if you have any other questions about the car.
RC America - XRAY USA - Hudy
Alamo City Racing Club - San Antonio, TX