if you did the mid lenght, o/r x-pipe, catback there is probably 20hp there.
give or take a couple hp.
you have to remeber mods don't always stack. a stock car may make 8hp with a mide pipe and 9hp with a catch back but 13hp with both. if that makes sense. you can't alwasy just take the bolt on face value and stack them all up. you have to make all the mods and see what they come up to.