I have a noise in my 83 n/a that only happens at about 2500 RPMs and above, and only when driving (doesn't make the noise by revving while sitting still). It's kind of a vacuum whooshing sound ("pffshhhhhhh") - fairly loud, I'm pretty sure it's exhaust related. One reason I am convinced of this fact is that it began happening after I was pounding and tweaking on the exhaust tip trying to remove the one that the PO spot welded to the pipe.

OK, so here's my theory.. Knowing how the L28's have a tendency to twist when torque is applied, sometimes loosening or even breaking the front and rear manifold bolts - I'm thinking this may be my issue.. Does this sound right, and is the sound I describe what you would expect to hear in this situation? The only manifold bolt I can seem to find is the rear one, and I haven't tightened it down yet, cause I don't have a torque wrench, and don't wanna snap it.
I can't think of an effective means to track down the noise, since I can't duplicate it sitting still.
Are there any other issues that might cause this, or am I just going to have to deal with it till the new header and exhaust go on this fall?

Thanks,
~Scott

 

Guess I should'a asked something like: "Which do you like better, a 240Z, or 280ZX?" Anyway, I'm sure I'll track down the issue, was just lookin for any insight..