[2023_ZL1-AUTO]

Originally Posted by radz28

What do you mean? If you are asking what I think you're asking, you are comparing port injection (PI) injectors to your direct injection (DI) injectors - well - you referenced DI injectors when stating the XDI injectors. You are looking at two different things. If I am interpreting wrong: my apologies. In the case I am wrong - there is nothing wrong with tuning for any of those PI injectors. All the compensations are in the REFLEX controller that was likely part of the quote for your kit. You, pretty much, just tell the REFLEX how much the injectors flow, and it does the rest. There could be a little polishing, but it's minor. There's nothing wrong with adding the FICs, in conjunction with the REFLEX controller from THPSI

The FICs are the PI injectors for PORT PLATES from THPSI. Those FICs are what are ADDED (the whole kit you were quoted by THPSI) to the DI to give you more headroom. The XDIs I believe you are talking about, would be direct replacements for your OEM DI.

What it seems like you are asking for is how to compare your options: upgrading the OEM DI system (injectors and maybe a pump) which look like lists for ~ $5900 for the 50% injectors and LPE HPFP; OR - ADDING PORT INJECTION, which is the $3100 kit from THPSI that you were quoted above.

There's a good chance you'll need a low side ($1100 [DSX] to $1700 [Katech bucket and add-on fuel filter kit]) that you should think about adding into the budget. You'll also have to think about another $200-$300 in plumbing to add to the THPSI plate kit. If the XDI HPFP mounts the same as the OEM LT4 pump (wasn't there a kit out there that ADDED ANOTHER HPFP, run off the serpentine belt?...), I think that might be more straight forward than adding PI, but tuning becomes more complicated if I recall (though - I thought I remember XDI injectors being one of the better ones out there to tune). The THPSI requires some special tuning, too, but there are lots of people that have been doing that for a long time.

The point is to make sure you're thinking in correct terms and using those terms so you don't get conflicting information

JMHO

You are correct sir! I honestly think when I was editing my post for a misspelling, I wiped out a complete paragraph of my post, my apologies ! Yes, I was referring to "Is there a preferred mod between the two if your staying with stock CAM? Either upgrade DI and replace the OEM's injectors and add HSFP pump etc. vs port injection system, plates, injectors, reflex controller, aux pump.

Thanks and sorry for that!