Help w/ b18c werid noise

[CurbSide]

Any help would be welcome im a semi-noob so...

the car used to belong to my cousin but he went to china (work) i cant seem to get in contact with him to ask him about it so...

my engine as im driving will somtimes make a screeching noise. any ideas on what the problem is?
also sometimes theres a poping noise when im idle.

I've also noticed that my mpg is only 20-25 i believe i should be making better or am i wrong?

the car is a 2000 Acura Integra LS w/ a b18c (jdm gsr) Swap.
that he did himself recently. Now im afraid he did a halfass job.
the problem just started recently i've had the car for almost 3 months.

[Ninj4r]

The stock exhaust manifold has this little peg as a brace inside of it that eventually corrodes, and causes a rattle at certain vibration frequencies, commonly around 3000rpms... it could be that? is it a constant noise, or just at a certain point?

the mpg could be just because you could use a tune-up, wouldn't hurt..
change your oil, plugs, plug wires, etc.
mpg also depends on how you drive...

hope it was somewhat helpful.

[CurbSide]

thanks yea it rattles around 3000 rpm and i do drive ok... i think i made 25-30 mpg on my old honda accord so *shrug* thanks for the help i'll look into it im planning on getting it tuned next week and was gonna take it into a local shop to try and figure out whats wrong.