bubble backfire sound,out of muffler

I have a weird sound coming out of my muffler & my brothers nissan does it too,its like a bubble backfire out of the muffler,
it done it before & after I cut the cat off,
it does it when I start the car,cold or hot,I dont need to hit the gas,
but when I do,it does it even more,(as the idle goes down)
my computers not showing any codes,practicly everythings new,besides my fuel pump/tranny...
the motor sounds good,perfect idle,but you can go back to the muffler & hear,bubp,bubp,bubp,,,,bubpbubp,,...
its not a big problem,but I would like to have a nice smooth performance sound instead of having that crapy idle noise,
sounds weird,but I think it started doing it when I put my apc muffler on,
but my brother has a powertech muffler & his does it too,
I think I've read a post somewhere on this & never got to reading it,
someone was saying it was a lazy fuel pump,
but if anyone has any clues of what it is or what I should do let me know,

yea i'd like to know how to fix this problem also. same thing happens with my hatch

Sounds like an exhaust leak.

Maybe something with the valves? Does it seem to run okay?

it runs fine,I've adjusted the valves already,
but I do have an exhaust leak,from my headers,but I got my exhaust before my headers,
& when I put my exhaust on I put it on with clamps,soon had it welded,but the weld was never air tight(all the way around the pipe,)
so maybe it is a exhaust leak,
my brothers nissan also has a leak near the manifold,
I'm waiting to get the money to have a fresh straight pipe all the way back,
but I have no idea of what it could be,
thx for any suggestions,

well when i installed my new exhaust it had that problem, so im not sure its an leak

i had this prob in one of my cars - it did it when i had no exhaust from down pipe back an i also had small fuel leak - so i would assume its one of those - i think it might be the fuel - there might be a pause in the fuel pressure when u try to start it an its making a bloop noise right? an after the fuel builds up it makes that noise then starts.....

mine makes the bubble noise when its idling

wheres your exhuast leak? is it the header?

im not sure, but im guessing it is

wheres your exhuast leak? is it the header?

yes,I have a leak in the headers,4-2(gasket)-1
but it was doing it before I cut the cat & before I put headers on,
but it never did start until I put the exhaust on,
I started with taking the factory muffler off & putting a staright pipe on it,it made a little better sound,but I've always had a leak,because I had it held on with clamps,so even when I took that off & put a performance muffler on,it still had a leak,because the person who welded it on,didnt weld all the way around the pipe,so it did have a leak,
& when I put headers on & straight pipe,I've always seemed to have a leak, :banghead:
& Ive had all the pipes finally welded together,except for the last leak,& its between the headers,because I didnt have any gaskets,
so maybe it is a exhaust leak,
& I'm pretty sure I dont have a fuel leak & if I did,it would be coming out the tank,because my cars motor is realllly clean,& I make shore everythings good in good shape,
& it only does it as it idels or when I shift(let off the gas)
it doesnt affect the way I drive,the pedal,fuel,but it may affect the performance(i dont know)
thx for all the suggestions--

so it sounds like you just need to put a gasket on the header - i would try that an ya never know it might stop - plus they aint really expensive plus ya need one....an exhaust leak causes power lost reguardless ...hope ya get her purrrin good,
good luck