I almost ordered the Radix this morning, but held off till asking a few questions. What size pulley should I buy with my current truck setup? (see my sig.)

What size pulley comes with the Radix? Should I consider upgrading it right away?

Thanks guys.

 

Your set up is close to mine. I have a Radix in the garage-awaiting install. I have a 3.4" pulley coming for it because the previous owner had a 4.8L. The 3.4" pulley is what comes with the kit new for a 5.3L. You will make 6 to 8#'s of boost with it. Get a smaller pulley for more boost, just make sure your engine can handle it. I can't speak from experience yet but everything I've read from other users tells me the 3.4 will make enough boost to make you happy. If you get one on real soon, let me know how you like it. I will probably be waiting another couple weeks until I get my transmission beefed up or replaced.
Chris

 

As Baumgarden posted. 3.4 is what comes with the kits for 5.3L's. It will put a smile on your face there. I put a 3.25 on at some point and it built 8 psi. Would see 9 to 9.5 sometimes at shifts. Since my cam install I'm back down to 6.5 psi. Don't believe I'll drop any further.

 

I've got another question too. Can I use my K&N cone filter or do I have to use the stock air box?

 

My opinion is that you should initially install the Radix as it comes out of the box, with the stock pulley and tune. Make sure it is running properly before you do anything.

Be aware that changing pullies changes your tuning requirements. You won't want to rely upon the knock retard capabilities of the PCM to keep your motor from running lean and potentially having problems. If you decide to change pullies, you should get a new tune. Again, my opinion.

About your K&N, I would run the stock air box at first, just to ensure everything is running properly. Once you are sure it is, then make your changes. My opinion, of course. The reason I am conservative is because (IMO) motors are relatively expensive to replace.

Good luck.