I'm building this 5.3 and I wanna get some advice on it... It's a budget build with a few extras. I have cathedral ported aluminum heads for it, brand new aftermarket machined intake, stage 2 cam and I'm getting a LS Holley Terminator for it... I'm gonna be using a 400 turbo tranny with a stage 2 shift kit... I'm about to maybe spend the money to upgrade my injectors to 42 lbs... Should I spend that money or should I use it elsewhere?

 

Unless your engine needs the extra fuel flow, and so far it doesn't look like it UNLESS you plan major mods, spend the injector money elsewhere.
Which year is the engine? Gen III or IV? Even the earliest Gen III (1999) came with 21.8 #/hr. which will support over 400HP.

 

With an aftermarket intake and ported heads, there's a strong chance that once you start throwing timing at it, you'll be above 90% duty cycle on injectors, if not already maxing them out. If you're trying to squeeze every last hp you can out your set-up, you'll need larger injectors. If you're wanting to DDit, you'll also need larger injectors because for a DD, personally, I don't want them to be operating over 85% duty cycle. As far as the size of the aftermarket injectors that you end up choosing, for as small as the difference in price is, you may as well just go ahead and buy 60lb/630cc ones for literally only a few extra dollars. Your set-up will be fun at first, but quickly you'll start thinking of a power-adder (literally ALL of us always do), and at least with the 60lb injectors already in there, you'll have enough fuel already there to add a small turbo or a shot of nitrous without having to pop for all new injectors. I would, however, start the tuning with the OEM injectors in there first, and just see what you look like when you start adding timing.

 

This is not good advice way overkilled your setup!!!

 

60 pound injectors are terrible advice at this point based on your stated combo ad mentioned above. I'd get it running with what you have now then if you add a power adder get new injectors.

FWIW - I had 26 pound injectors on a ~418 whp heads & cam LS1 set up for 15 years & 130,000+ miles from 2002 to 2017. It wasn't "perfect" or ideal but it sure wasn't worth the cost to upgrade at the time to #36 and cost to retune.

For LS1 fbody cars:

1998 LS1 injectors were ~28 pounds
1999 to 2000 LS1 injectors were ~26 pounds

2001 to 2002 LS1 injectors were ~28.8 pounds

For daily driving & basic heads, cam & intake upgrades any of the 26 to 28 pound injectors in good working order can support ~425 whp to ~450 whp...we did it back in the day all the time.

Later on ~465 whp LS1 build I replaced a set of #28.8 stock LS1 injectors with #42 injectors. The tuner told me we could have gotten by with the #28.8's

 

It's a 2006-07 model vortec out of a Tahoe I believe... I'm trying to squeeze out as much HP as I can... I've got about a 4k budget building this thing and a thousand is pretty much gone just on engine and tranny, I'm buying a complete rebuild kit for the motor bc I have it torn down to the block anyway so I may as well rebuild it. The parts I listed in the original post are give run me around a grand plus the $1200 for the terminator... My budget is running low...I can save over $200 if I don't get these injectors but idk where to spend the money to gain a few more horsey's....

 

Bigger injectors don't gain power unless the engine is making more power than they can support.
You likely have 29.6 #/hr injectors which are more than enough for a near stock 5.3, unless you are expecting 600HP or more....

 

tuning.

 

Rear gears and a good torque converter to match your combination.

 

I put the gm 50lb flex fuel injectors on my 5.3. Cheap and easy to tune. I did this for future 6.0 build. Very easy to find injector data on them and easy to find. With my 5.3 they are around 60-65% duty cycle at wot.

 

well I do plan to DD this thing and put my SN95 in the shop for some repairs... However I want this thing to absolutely fkn thump, do you all think I can get that out of that stage 2 Truck Norris cam?

 

Cam it for the performance level you want. Don't buy on sound. You're not in high school anymore.....