There's often some debate about what works best, to buy a more expensive guitar or to find something cheaper and mod it to how you like. Essentially, with this pickup I was able to turn a pretty cheap guitar into something that sounded extremely more professional, within about 30 minutes and would say for a combined total of £140, created something of quality you can't buy at the price.
The guitar I installed it on was a Squier Bullet Strat, which I bought to sit in one location due to my other guitars being elsewhere. The workmanship on the cheaper Squiers is great value for money but the pickups still leave a lot to be desired due to the low guitar cost. I decided to upgrade the pickups to rectify this and chose the Jeff Beck humbucker from Seymour Duncan.
Quality: In terms of pickup quality, it is what you'd expect from SD. Top grade, there's little more to be said. This thing will last an eternity.
Sound: I opted for the SH-4BK due to its more rounded tone, yet still a bright one like you'd expect from a Strat, adding some tight crunch to the HSS pickup formation. There is some good sustain and clarity from the pickup. The cleans are glassy clear with a subtle shimmer. I'm not going to give 5 stars as its not the best pickup Seymour Duncan have ever created. While you get some impressive tones, its not jaw dropping, like some pickups I've heard. Don't get me wrong though! It sounds awesome and if you're anywhere in the rock/blues (or even Metal I'd say) arena this will do the job perfectly. It was miles better than the stock pickup of course.
Installation: I've installed pickups before so this was no issue, but it really isn't that hard, especially if you're simply replacing another passive pickup. Make sure you have the right tools: soldering iron, Phillips screwdriver and it'll be quick and painless. The diagrams online make this easy, too.
Overall, for the price this is an amazing piece of kit. I don't understand why more people don't mod their cheaper guitars to sound crisper, cleaner and generally more awesome. This pickup fit the guitar and playing style well and I'd totally endorse it for this or another similar purpose.