Just finished having my Magnaflow stainless system installed. Took about 3 1/2hrs by an experienced muffler guy, who is the muscle car exhaust guy in these parts, and was done at the shop with all the right equipment available. I was there the entire time and lots of modification had to be done but it turned out great and my new TTI tips eventally were positioned perfectly. With the small block 340 system #15851 here are the issues you can expect to run into so be prepared:
The system itself out of the box fit great from the TTI headers back with the X pipe to the mufflers....
I had a similar experience with mine when I bought it back in 2009.
One guy at a local shop hacked it in ...it was on the car but all crooked and offset to one side.....
So I had it redone by a second shop after I ordered new collector-to-xpipe pipes.... who took 3-4 hours on it.....he said it was anything BUT "bolt in".
Had to tweak the pipes going from the collectors to the x pipe...same with the rear pipes. ANd I have a plain Barracuda, so it exits under the valance....
I love my system...the sound and the look....but glad I took it to a pro. Well worth the $.