There should be a pipe coming from the back of the heads to the emissions equipment. It is common that people rip that out when they remove their smog stuff, but forget to plug the back of the heads. So as the car revs, you hear the exhaust noise.
You can probably easily see it. Rev it up and listen for it. Then put your hand over the hole while it's cold and it should go away.
You could have an exhaust leak from a blown header gasket(s), or your H pipe to headers nut-bolts are loose.
__________________ 89 GT Hatch: Custom M90 Supercharged w/ Ported Trickflow Trackheat Heads, Stage 1 cam, Streetheat lower / Sheet metal upper, Tweecer RT & PLX Wideband, 75mm TB, 1.6 Roller rockers, 3.73s, MSD 6a, Canton 7qt Pan+ Windage tray, 36LB Injectors, 200 amp Alternator, 75mm Pro-Mas MAF, 190lph fuel pump,Spec Stage 1 Clutch,SouthSide LCA's, Pro 5.0 Shifter, Steeda CC Plates / Springs, FMS Aluminum Driveshaft, New T5 w/ 2.95 first gear, Underdrive pullies, Zirgo 3300Cfm Elec. Fan, AFCO alum. radiator |