quotes from tireburner163...
"Stock: 260hp
Off-road h-pipe and cat-back: 280-285hp....."
Thats 20-25 PEAK HP you are claiming with an H or X pipe/catback setup.
"Yes a h-pipe and cat-back can add 20hp"
Yes, CAN, but not on a stock 99GT.
"Get the H-pipe dude, it's worth a lot more than 6hp."
Yeah, your right, thats 7 peak HP.
Bullitt Prochamber dyno
Again, I agree that an H or X-pipe is a great mod, but I don't think you will have 285HP with that and a 3-5 peak HP cat-back.