Put friend in drivers seat(or anonymous stranger will do), have them play with the accelerator, you slide under the front and listen carefully. Determine whether it is coming from within the motor or from the exhaust pipes. Typically it is from the heat shields but your discription is very vague, you might give it a little tap, tap, tappie with a rubber mallet in places along the exhaust pipes.
White gauges and Temp Cntrl, OHCw/Buggman LED mod,
Bosch +4, Accel Coil Pack, MSD6AL, Walbro, HiFlo Fuel filter,
Custom Ram Air, K&N, Ported / Matched intake, JBA 9mm wires,
Tweeked FPR, EBC 6k's, DynoMax-S CatBack, Jet-Chip, Reflex shocks,
New Anvil Mounts, Timbren's, Optima Yellow, DB 220A Alt. w/4g. jumper,
Western snow plow, More2Come