i plan on finishing my ls swap this weekend. i want to use a exhuast manifold from a 1990 integra cuz the o2 sensors are in the right spot. i know this manifold is going to be too long. does anyone know how much i need to cut out of the downpipe for this to fit like stock exhuast? i'd like to cut it to the right specs and drop it in, rather than have to put it on, take measurments, take it off, etc. i have a lot of stuff to worry about this weekend for this swap. can some one help me?

thanks,
-kyle