Need help with my SR20 det red top Silvia
 

The car won't rev past 4500 rpm. Checked all the hoses and there are no air leaks, so I have no clue what the problem is.

could be your maf

i second that

clean your maf, and or try it out on a freinds car and see if his/hers does the same thing...

timing timing timing

I already cleaned the maf and it made it a little better but it still does not go past 45xx revs.

try to switch with a different maf.

I am going to take a wild guess here but check your 4th and 5th gear sensors. Make sure they arent shorting out on each other. I say this because 4th and 5th have gear based rev limiters and one is at 4500. Forgot which one, but either way check them.

Make sure you have enough fuel pressure ;)

also try checking the MAFS wiring if you recently did the wiring. Then check to make sure the connector is connected securely.