Observations based on my personal experience with these shorty header options.

SLP 1 3/4" uncoated, non emissions, single cat Y pipe. These were on my 88 IROC when I bought it. The stainless steel still gets mild surface rust after years of use. The collars that hold the flanges to the Y pipe are junk steel and if not coated rust quite badly. The Y pipe is also junk steel and rusts. Construction - while they have 1 3/4" primaries the ID weld bead, while nice and solid, reduces the opening size considerably.
Installation is a bit tricky, I have no AC and can slide them in from the top but it does take some work. I personally didn't have a rubbing issue on the steering shaft until I switched to Percys Dead soft header gaskets which are thicker and now I have a very slight rub. The Y transition into the single pipe for the cat is pretty decent. Overall they seem like a decent option if you can get a good deal on a set.. try and get the coated ones. Used are obviously the only option at this point.

Edelbrock 1 5/8" uncoated, emissions compliant. I got these on a parts car. Not sure how old they are, but they are quite rusty. They are pretty light in comparison to the other options. They just don't feel as well made either.
The Y pipe transition is an absolute joke. Fit and ease of installation and removal seems a bit better than the SLPs because they are smaller overall. I had planned on using them since I didn't even have the stock manifolds but, I'd never purchase a set. I think there are better options. If you can find some used for real cheap I suppose they are an upgrade over stock.

Dyno Dons 1 3/4" coated, non emissions. I picked these up today to use instead of the Edelbrocks. Hands down the winner of these three. Construction is much better. The ID weld on the primary tubes is far nicer than the SLPs. It looks like someone took a set of SLPs, said ok this was a good start, now let's fix what is wrong. From my understanding that's basically what Don did. I would have NO hesitation what so ever in recommending these. I can't comment on fit as I have yet to install them, I have heard nothing but good things in this regard though.

 

Exactly what Don did. He is still making small improvements. With my next build he will be supplying the headers. I plan on making past 400rwhp.