ok I have purchased barrel tapered Magnolia shafts and was wondering if I had to cut( 1" off) them would it affect the arrow due to the tapering being even about 4" on each end?  

A 4" taper isn't much, I always put a 10" taper on a shaft. Doesn't matter if they were single tapers, barrels, or breasted shafts.
Yes if you cut an inch off it will affect the taper, and the spine.
Spine wise it will matter a few lbs, you probably won't notice a difference.
Magnolia, how do they smell, flowery?
Jim

I used to shoot the Quillian Superceders but I don't remember which end I cut (point or nock).  They were some fine shooting barrel tapered arrows and I never seemed to have any trouble tuning with them.  I bought a couple of dozen from Don Stokes here over a year ago and just haven't put them together 'cause I don't want to screw them up.  I'd be interested to see what you come up with and what your impressions are with your shafts.