Hmm, Fed Ex truck injectors. . .Maybe AC's (160cc)? Those would probably work great for the D66 turbo. Hypermax makes an H2E kit for the OBS trucks. . .but those sticks will be a little on the small side for that turbo. I dont think they would be B codes cause the factory oil pump wouldn't be able to push them at all if he was running a tune.
What is he running for a tune?
What kind of mudding does he do? Mud racing? Just running around the back woods? I'm curious as to why the "lag" is an issue, or what would be perceived as turbo lag. Realistically, even AC's should work OK with the factory charger on the OBS, they have a pretty good sized exhaust housing. Is he running into issues with the EGT's, or is he just looking to make some more power out of the truck?