So this is the frustrating part of posting on this site, people not actually answering the question. I didn't suggest I was going to get a new DC. I simply want to know the best pipe to use for the best bang for the buck. Instead of me installing something and regretting it, I thought I would post on here.
Please understand that a very basic rule of the Internet, and forums in general, is that while you may ask any question you want, you do not get to choose the answers that you will receive nor what other aspects of the topic a thread may evolve into...in part because those answers are to a much wider audience than just yourself. One must understand that while you may consider a thread to be yours and yours alone, the thread, the subject being discussed, and any replies that may follow, are really oriented at a far greater audience than just you as the subject matter is written for a world audience also interested in the subject. That is how knowledge gets disbursed far and wide. If the replies were so narrowly focused as to have meaning only to you then no real knowledge is disseminated and there is little value to asking the question in a public forum, even less reason for others to follow the thread, since the answer may literally be so specific as to apply to a singular person in all the world (depending upon just how specific the original question and subject may be). None of this is meant to be taken personally, nor should it, just remember that the primary goal of sites such as ours is to share applicable knowledge to any who may discover the thread, whether that be today or ten years from now, and not just for the benefit of the original poster.
The main reason you are receiving suggestions regarding upgraded dust collectors (DC) is because a 1HP DC is only marginally effective (and even that is assuming one of optimal design) due to the limited volume of air they can move and the limited static pressure they can generate. As such a 1HP single stage DC is not really well suited to being plumbed into a workshop but is best treated as a mobile DC where the absolute shortest possible length of hose between the DC and tool is used, preferably less than a 10ft length if using smooth walled flexible DC hose (even less if using corrugated drainage pipe), or at least the absolute minimum one can get by with -- and that generally means a single length of flexible hose that is moved from tool to tool as needed rather than a plumbed shop. Plumbing a shop really starts out at the 1-1/2 to 2HP range for single stage DCs (2-3HP for cyclone DCs) where you can better afford the static pressure losses from extended runs of smooth rigid piping with minimal lengths of flexible hose at the tool and still maintain adequate air velocities.
Whenever plumbing a shop for dust collection you want to use a rigid ducting system that has as smooth an interior as possible and which provides for wide sweeping turns and branches so as to keep airflow as laminar and undisturbed as possible as any disturbance both increases static pressure losses, reduces velocity and volume, and presents opportunities for heavier waste to fall out of the airstream and collect, possibly leading to clogs if the air velocity drops too low within a given section. Clearing such clogs can require disassembly of the ducting, once the obstruction is located, and that is very inconvenient so you want to avoid such by utilizing best practices to the extent you can practically. Be careful if using general HVAC steel ducting as the cheaper alternatives can have very thin walls and can be collapsed easily by more powerful DC systems if all gates are ever left closed by accident or is impacted while moving wood stock or tools about your shop -- destroying your investment and time. While heavy rigid ducting designed specifically for dust collection are the best to use, they are also quite expensive. That expense leads many to use the heavier HVAC ducting as well as alternatives like PVC (either solid PVC/ABS or the foam core DWV, drain waste vent) PVC piping to save money while still getting reasonable performance if implemented wisely. If using PVC (and related) pipe, keep in mind that many bends in Wyes, elbows, and the like, can be much too severe if the fitting used was intended for water transport and can create excessive turbulence, so try to use fittings geared towards waste lines, or even electrical conduit, where the bends and curves tend to be much more graceful than with fittings oriented towards water transport.
When it comes to flexible hose it is best to use the smooth walled spiral reinforced polyurethane hoses as foot for foot they incur the least amount of loss for a given length of hose and maintain higher air velocity. Corrugated drainage hose, while often used, is about the worst of all the flexible hose choices one can opt for, but often gets used simply because it is dirt cheap, though such can be acceptable if you are using a more powerful DC and a very short length of such hose (for example, a 2-3ft section between the tool and fixed rigid ducting). The real issue with corrugated hose is the corrugations themselves as they create a lot of disturbance to airflow, especially around bends, and that greatly reduces both the velocity of the airflow as well as the air volume and breaks up the laminar airflow that one wants to preserve as much as practical. However, even the most ideal and highest quality flexible hose is many times worse than rigid smooth walled ducting -- even 10ft of the best polyurethane hose is probably equal in losses to about 30-40ft of rigid duct of the same diameter (there are charts of estimated static pressure loss you can refer to both online and in books on the subject, if interested).
The actual subject of efficiently plumbing dust collection systems is really quite involved and is focused on using the largest practical diameter ducting while still maintaining a suitably high air velocity in that larger duct and gradually stepping down in size along the way (such as with branches) as static pressure losses begin to rob one of the needed minimum velocity in the larger duct and can require partially opening bypass gates at the ends of a run to ensure adequate air velocity at all times in the main trunk lines, and so forth. There is an amazing amount of science and engineering involved, especially as such systems grow in size and complexity. Fortunately, one can get away with a number of sins in a small personal workshop since we are not governed by OSHA exposure limits and we can use ambient air cleaners to effectively scrub from the air much of what we failed to capture at the source in terms of very fine dust (the harmful portion), but it is still best to capture fine dust at the source as best one can. So do the best you can and use the best materials and practices as your shop and budget allow.
You will want to seriously consider upgrading your DC air filtration to a 1-micron bag or canister filter as 5 microns (if that is what came with your DC) is large enough to allow the very most harmful of fine dust to escape from your DC, negating one of the greatest arguments for dust collection in the workshop as wood dust in the range of 1-5 microns is a known carcinogenic and can severely exacerbate breathing issues if you have allergies, asthma, or other respiratory disorders. It can be especially problematic if one works with exotic African woods or spalted woods as they are some of the most dangerous to inhale and a good 1-micron filter goes a long ways towards reducing those risks. The downside of installing a 1-micron filter, however, is that it will further restrict the volume of air and static pressure that your DC can generate, how much will depend entirely upon the amount of surface area the filter provides, which is where a deeply pleated canister filter is most helpful as they help to maximize filter surface area and minimize those losses while still providing you all the health benefits of the improved filtration.
Adding a Thien filter in front of your DC will further restrict the airflow and static pressure available to you to work with as there is no free lunch and the work done by the Thien prefilter is essentially obtained by robbing some of that power from your DC. How much of a loss will depend heavily upon how efficient and optimized a Thien filter design you can build. Some of those losses can be offset by reducing clogging of the DC filter bag or canister, though in the case of a canister filter the benefit will be less apparent since they provide considerably more filter surface area to begin with and often include a paddle you can rotate to knock accumulated dust off the filter at regular intervals. If you upgrade the DC filter I would first start out without the Thien prefilter and then evaluate after some use whether or not you feel you really need the benefit of the Thien filter as you may find that you do not unless your impeller is regularly getting clogged with oversized debris. If you do not upgrade your filters then you will almost certainly want the Thien prefilter, but you really should upgrade the filtration -- and possibly even add an ambient air cleaner with 1-micron filtration as well -- if yours, or your family's health is of any concern (but especially if using exotic or spalted woods), particularly if your shop is attached to your house.
Good luck and I wish you all the best with your shop upgrade!