What type of mods? You dont really need it to be tuned for basic I/H/E setups

 

i meant upgrades not mods. i'm just wondering what my horsepower is now with the upgrades i have done to my car(i still need to put my headers on).so i guess dyno is what i need to do huh? i've seen it on horsepower TV when they upgraded that civic except they added a NOS kit with that project. no..i'm not adding nos on mine

 

you want very high velocity with very low backpressure. That's the key. Just go as large as possible before you run into delamination (turbulence) of the air stream through the exhaust.