I have an 89 S5 T2. I want to upgrade my injectoers. What size should i go with? I have full exhaust and plan for more mods. I dont wanna get 2 miles to the gallon though, but i wanna keep my motor safe. What size injectors should i go with for the primarys and secondaries. Thank you. I plan to have around 300- 350hp when finished.

 

Dude, you want to go with larger fuel injectors, but you don't want to take a hit in mileage?
I'm sorry, but more power means more fuel.

Also, if you try to give the engine too much fuel for it's needs, it's just going to foul spark plugs and the motor will not run.
If you're getting 2mpg, you've got a fuel leak somewhere!

Also, you can't just drop in large injectors and expect the stock ECU to run efficiently.
Minimally, it takes a fuel computer (i.e. A'PEXi S-AFC) to jack the pulsewidths down so the stock ECU can handle the larger fuel injectors.

BTW, 350hp at the wheels will require almost 2000cc/min of fuel to safely deliver...


-Ted