18x8+38 on the front is pretty weak.
If you want to fill out the guards 18x8/9 in the range of +25/30 will do the job without neeing to do much in the way of guard work or camber.
Too much positive offset may hit brakes, suspension.
Basically positive offset means the rim of the wheel is sitting further inboard than if it were centred with the hub. Negative offset means it is sitting outward from the body of the car.
You're probably best off finding something in the low to mid 30's if you want to fill out your gaurds a bit better.
This is a 17x9 +38
This is a 17x9 +22
I had this issue, replaced cluster with the one out of parts car and then the speedo wouldn't go above 60kmh. Swapped out the speedo and now I've got one perfect cluster and one fubar one
Nope, SR/RB25 run side feed injectors. Rb20/26 on the other hand run top feed. This does mean you can use GTR 444cc injectors though you will still need to run a resistor pack.