Hi. Im thinking about changing my stock injectors and installing 720cc injectors. The car is full OEM except the fuel pressure regulator and the HKS boost controller. At WOT, at 6'5k rpm, my A/F ratio is 12.1 - 12.3 and boost 9psi. Could someone recommend me injectors for a S4 turbo2? Is it necessary to change the 4 injectors or could I change only the secondaries? Thanks in advance

 

720’s all around is a good idea and gives you headroom to 12 psi or a slightly larger hybrid turbo. But the real question is what ecu/piggyback/stand-alone are you going to use?

 

Hi. Now Im using stock ecu, 2'5"downpipe and fuel cut defender.thanks

 

Stock ecu, could try just 720cc secondaries and check afr’s but that’s 30% more fuel on the secondaries so should look into controlling afr’s.

In case stock ecu isn’t enough, I’d recommend a used rtek Ecu 1.7-1.8, or at least a safc to adjust afr’s.

good luck.

 

Hi. Where can i buy rtek1.7? I cant find a web to buy this chip. Thanks in advance

 

They are discontinued, hence my recommendation to source a used one. Website was under digital tuning.com if you want to read the details on each option.


Other options would lead to either just a safc, or a full standalone like a power fc, haltech, etc.