The title isn't much to go by, but recently someone hit me in the rear of my Integra which ended up totaling it.

I found a shell and put the LS swap from my Integra into this 94 EX. Ever since then, the RPMs on the tach don't read with the motor. The motor will fully rev out to 7400rpm (or whatever the stock LS goes to), but the tach will redline at 5500RPMs. I always wondered if the fuel pump would of caused it not to pass 5500rpms due to the shell sitting for some time (I'm not mechanically inclined, so I'm just guessing) but last night I had a run in with another LS and mine held its own. So therefor, I'm completely clueless.

The motor idles/reads normal (900/1000rpms) and when driving on the interstate it reads 3000ish RPMs (normal)

Sorry if I did a horrible job at trying to explain my problem, I just want to try to get this fixed, even if it isn't that big of a deal (doesn't affect the drivability of the car, I DD it) When we did the swap, the new shell recieved everything from the Integra (ECU, harness, ect so it should run 100% OEM)