Will 5.7 tbi injectors work in a 5.0 by just dropping them in without modifications. They are a lot easier to find.

Also where the heck can I find a tpi setup are they expensive.

 

I have those injectors for the 305. Will they work, not without a re-tune. You'll be a bit rich at idle. I'm not totally versed in TBI maybe someone can comment on if the ECU will support the larger injectors.

Why swap to TPI? IT's expensive.

 

Well I always thught they used the same ecu and the 55 injectors are not much bigger but would I thught maybe it would run better.

 

I concur with the above advice, you are better off to first get yourself an ALDL cable & an inexpensive program like TunerPro-RT so you can get a look @ what is happening w/your engine, this is a fantastic diagnostic & tuning setup, that can save you lot's of time & cash in the long run.

It never hurts to consider the injectors for improvement as the stock ones can be quite mis-matched from the factory & over time, become dirty drastically affecting performance.

Consider instead, replacing your OE injectors w/a set that have been professionally cleaned & matched for your application.
Add an adjustable fuel pressure regulator & you can make quite reasonable strides in getting the most from your engine.

Injectors Plus offers such units, as well as a company called WitchHunter
A quick Google search will take you to either company's website where you can find their services offered & prices.

Your ECM will have no problem supporting larger injectors should in the future you make engine modifications requiring such.

Again as stated above, this requires the ability to tune the ECM.

 

I just spoke with the tch folks over at CFM-Tech.com about thisd same topic. They do not recommend replacing 5.0 injectors with 5.7 injectors unless you recalibrate your ECM. They said that it won't know about the larger injectors unless you do this step. They sell refurbished injectors, but they are flow matched to within 1% of each other. Their price on these is $169.95 for the pair - not bad.

 

The LO3 stock injectors are 55#.