Need help buying exhaust!!!!

Ok guys.....I have a 1972 duster with a 318 LA block and 904 tranny.

My springs have been relocated inward with the welded in leaf mounts.

I have summit long tube headers on my car.

I am looking at the summit 2.5" header back exhaust system that included mufflers and all pipe and hangers and all that good stuff.

I have a couple questions though for everyone that I am hoping can be answered.

question #1- Since I have summit header and this is the summit header back kit made for my duster.....will it be a direct bolt in match up? I don't want to have to take it into a shop and have it rebent up or something stupid like that LOL.

question #2- since my springs have been re located inward ,will that interfear with the exhausts routing position? or is the (common) spring relocation not far enough inward that I need to worry about any interference?

question #3- has anyone here ran with this exhaust set up and do they have any comments they would like to mention? also what kind of sound does it produce? any videos?,how is the fitment of this system in our A-bodies?

question #4- what kind of power gains (if any) would I be looking at from this particular set up and is 2.5" good for my combo? ( 318 punched over to a 323 with dish poly pistons (semi hemi's) ,milled high compression 1967 318 heads,mild cam,long tube headers,edelbrock dual plane intake,edelbrock 600 cfm 4 barrel,2200 tci stall and a few other odds and ends).

Hope I gave enough info and that someone can give me the answers I am looking for.

Also, funds are low so this summit system is about all I can afford, I would eventual bump up to some different mufflers but for now they will have to suffice.

Thanks!

here are the links to my set up....

HEADERS I HAVE- http://www.summitracing.com/parts/SUM-G9040/

EXHAUST SYSTEM I AM LOOKING AT- http://www.summitracing.com/parts/SUM-680144/