Hey guys, my son has a 04 GT and wants to put headers on it and later some catbacks...SLP Loudmouths. His question, which I can't answer, is how much horsepower gain should he get with headers and catbacks...generally speaking (ballfield numbers)?

 

stock his car will probably put down 210-225rwhp. with the longtubes, midpipe(which he will need with the longtubes), and slp catback...looking at maybe 250rwhp, give or take maybe 5rwhp. sound about right???

 

i dont beileve he will be anywhere close to 250 with only lt and a midpipe at most see a 5-10 hp gain

 

i would say bout 25 -45 give or take cause i did notice that u have a tuner and i figure ur gonna retune it wit the new exhaust system and u didnt mention a mid pipe which u do have to change for lt and should change even if u get shortys....

 

I just had my headers installed last week. I noticed a huge difference in mine, I have the BBK shorty ceramic coated and they say tuned. I would say around 20hp as long as u have a air intake and a full exhaust. But you should really buy the ceramic coated no matter what brand you buy. They flow all the heat out rather than stainless which gives off. And for Gods sake dont buy the Ford Racing Headers they suck!!!!!!!!!!!!!!!!!

 

Hey thanks guys for the input. Your insight has been very helpful.

 

7rwhp headers 10rwhp midpipe and CB... if he is a stick. he is prob at like 225rwhp stock. so he'll be at 240 or around there.. and with a tune, 250 TB/PLENUM would put him at 255ish and than pulleys would be about 260.. and that would be full bolt ons

 

Thanks for your input I appreciate it.