Does this sound like an exhaust manifold issue? (355)

I have a 96 355B and I've suspected for a few weeks that I might have the beginnings of manifold issues on the right bank. At idle, the exhaust does seem quite noisy (stock system). However, having never head another 355 with a stock exhaust, I have nothing to compare it to. But, it does sound like the exhaust is blowing slightly. Also, and more tellingly, every now and again, I can hear what sounds like a 'spit' from the manifold area on the right bank. This is with the engine cover open and the car idling. Happens infrequently, but I have heard this very distinct sound on a couple of occasions. I suspect that I may have a slight crack in the manifold, but of course, I can't be sure. Also, when the car is started from cold and I gingerly press the accelerator (when inching out of the garage), the engine 'stumbles' a little (almost as if there's a inlet manifold vacuum leak). It's fine when the engine has warmed-up a little.

I did take the car to a local specialist last weekend and he had a listen to it. He was of the opinion that nothing was wrong, but I'm still not sure! He was listening to the car with the engine hot, so it is feasible that a hairline crack in the manifold would close-up due to heat expansion with the engine hot.

Is there any way to 'test' for a leaky manifold without dropping the rear subframe to visually inspect? I'm thinking in terms of EGT or temps around the manifold? Would it throw the lambda off on the affected bank? This is bugging me now and it's niggling at the back of my mind. I want to determine, conclusively, if I have a problem or not. If have looked for signs of insulating material blowing-out, but it all looks fine.

Thanks,
Ian.

 

Anyone?

 

Found the cause of my noisy exhaust today... sheared clamps around the junction between the cats (both sides) and the exhaust box. Will order new billet clamps and, hopefully, the car will sound a lot better for it

Thanks for the advice guys.

Cheers,
Ian.