whos an 5.0 exhaust expert

December 02, 2004, 08:50:06 PM

i put mac shorty headers on with a 2.5 off road h-pipe no cats
with a 2.5 mac cat back system ok when i have the car in park or neutral and i give it a little gas it sound all right but when im driving it makes a sound on the passengers side firewall l;ike if theres a leak of air coming out of some where buit its not from the exhaust it sounds like si si si si si si si and its very loud like if air coming out then stops out then stop but very quick

Re: whos an 5.0 exhaust expert

Reply #1 – December 02, 2004, 08:57:14 PM

I'd guess it's your air pump. It's supposed to pump air into the catalytic convertors, but without any it'll just pump air into, well, air...