Are you able to use a 02 or 03 rsx short ram intake from injen or aem ??

 

No, the 06+ Si has a MAF

 

you would need to fabricate your maf sensor in , i have seen people cut the tubing where the maf is on the car and shorten the k20a tubing and sleeve in the maf off our cars, but they were in both cases free since 1 of them was off my 04 rsx and givin to my friend , and the other was all of a $17 win off ebay including shipping in a friends 06 si. he only did it for the simple fact nobody made 1 at the time and is a honda tech that just plays with the car and drives the snot out of , to see if he can kill it..cheapest gas he can find an all..

but if you can get 1 for little to no money , you can make it work.