i've been told that i should get headers with 1 5/8 primaries and a 3 inch collector, should i stay at 3" from that point back. they're are many companies with 3" parts?

 

For a 305 that sounds good to me. If it was a 350 I would recommend 1 3/4" headers.

 

Do you have to remove AC stuff when going over to headers? Ive got a pair of headers for my car just laying around, but I dont wanna lose my AC just yet maybe after I get my 350 together. Which I dont know why, I have ttops which can keep you pretty cool on a hot day anyways.

*edit* I have a 91 camaro rs with 305