So I'm in the process of getting all my parts gathered up for my next major upgrade. My new setup is going to consist of using an LS3 car intake. Since my 03 is return and the LS3 is returnless I need to convert to returnless.
What kit would you suggest for doing so?
Also what are my fuel pump options for returnless system?

I'm running the LS3 injectors which are ~40lbs or so I'm thinking I'll need to upgrade as I'm looking at 500-550rwhp hopefully N/A. Any insight on that?

 

Your going backwards. Most people convert from returnless to return style, not the other way around. You won't find a kit to convert from return to returnless cause it makes zero sense to do so, since in a performance application it would be taking a step backwards.

Don't waste your time and money to do this, hang a FPR on it and be done.

Regarding the injectors, at 550rwhp N/A I'd run a 60lb injector. You might could get by on 44's since its N/A but why? The 60's won't have to work as hard and you'll have better control over them as the IDC won't be too high.

 

I agree with Blown06, don't change it.

 

Doing it to save money on rails is stepping over dollars to pick up a dime. If you absolutely have your heart set on it, a Corvette or 2003 S-10 2.2FlexFuel fuel filter will do the trick.

 

the s-10 filter wont do the trick i bought 1 thinking it would but it wont the feed is small male and the return is a larger male !

 

Would it essentially be the same involved as doing the LS6 intake? If so I could just get a lot of info from one of those threads. I didn't think it would make any difference in performance especially since the newer trucks have returnless now days but this would be the first time i've done any fueling upgrade so I have no idea.

Would I need new rails or what would be involved if it's different than the LS6 intake swap?

As far as injectors I'll buy at least some 60's and then upgrade them later when I plan to go F/I.

 

There is a way you can run the a aftermarket FPR to work with a single feed rail, your stock fuel lines.. It is the way I am going to run mine, should work perfect..