THAT, in stainless steel, would be nearly perfect.Dual in cat body works very well too. In fact the magnaflow/bosal high flow cat for a L30 305 Vortec van is identical to a TBI truck where it bolts to the manifolds and uses a high flow dual inlet/single outlet cat...
With aluminized pipes, it'll rot out in ~8 or 10 years, which may be perfectly acceptable. My Flowmaster aluminized cat-back system went a little more than ten years, but had rust holes big enough to push a kitten through towards the end. I got rid of the aluminized parts, replaced it with Stainless pipe and muffler several years ago.