Originally Posted by ol_Blue97
If it is a L-99 and you change your up-pipes it is worth it as you have more turbo options later on down the road and will allow you to easily use 3" plenums and a L-99 spyder when you deside to intercool your truck. You wont see more boost but it will spool faster with the tighter AR ratio.
If its cheep enough,do it but get the up-pipes and the spyder and 3" plenumbs if its a L-99. If its a E-99 get the spyder and sell it elsewhere as these are hard to find
More turbo options? It gives you the choice of a 38R... nothing else.
Early or late 99? Either way, IMO, not worth it. For the work involved there will be no real performance benefit at all. Yes, you might see a little more boost quicker. But for the L99 you have to change out everything turbo related, and I do mean everything- turbo, pedestal, up pipes (possibly the drivers side manifold too), intake plenums, intake Y, then you'll also have to snag the intercooler and install that or fab up an IC delete pipe since the OBS intake Y won't work with a late 99 turbo. You may have to push the firewall back to clear the turbo too. If it's an E99, you only have to swap the turbo, pedestal, and up pipes but again, not really worth it because there isn't hardly anything to be gained.
If the parts are free, I might go ahead with it but the juice just isn't really worth the squeeze for an SD turbo swap.