When you click on links to various merchants on this site and make a purchase, this can result in this site earning a commission. Affiliate programs and affiliations include, but are not limited to, the eBay Partner Network.
It's not going to run very well, because you're placing the O2s further back in the exhaust stream. They're set at a certain distance so they can react to changes in the air/fuel mixture, and moving them farther back increases the distance of the feedback loop. It may run well enough to get it to a tuner, but I wouldn't plan on keeping it that way for long. Not to mention, you're greatly increasing exhaust flow out of the engine, so in turn your engine's ability to ingest air will increase. If untuned, the air/fuel mixture could become dangerously lean.
For only headers, consider doing a mail-in tune instead of dropping big bucks on a dyno tune. I did a Frost mail-in tune for my stalled and bolt-on car and it turned out really well.
FWIW, I have a mail order tune on my Camaro with headers, high flow cats, and a BTR stage 4 LS3 cam, and it rips. I second doing a mail order tune, it's too cheap not to.