DT...
I'll do the best I can to offer you some suggestions and you will have to decide on what your choices are,after all,you are your own warranty station. .
1-Intake. .
I am a K&N user and have used their products on and in many applications. I have never had a failure due to one of their filters and don't expect to. When they are cleaned and oiled properly they will not produce the residue problems which plague alot of owners here who use them. The drop in version has been known to pass some dirt particles into the turbo,but,not for reasons some here have claimed. Most owners who have had this problem with the "drop" in version have had fit problems with the factory air box which allowed dirts to pass by the sides of the filter. I am certain if you do a search here you will find enough reading and bantering about it to make your eyes get crossed.
Now,another alternative to the "drop in" style filters is by using the more TDR Common BHAF(Big Honkin Air Filter) which is about the same cost and filters as good or better than your drop in filter. Its a cannister style filter in which you remove the factory air box and slip the tube onto it and tighten it down and away you go. There is also a waterproof Outerwear's prefilter available for it if you desire. Here are the BHAF part numbers if you would rather one of these.....
BHAF Part numbers
Fleetgaurd # AH19037
Wix # 42790
Napa # 2790
Carquest # 87790
Donaldson # B105006
Baldwin # PA2820
John Deere # PMAH19037
Big A # 93790
CATERPILLAR# 3I0005
FLEETRITE # AHR819037
HASTINGS # AF1012
LUBER-FINER# LAF2531
2-Injectors. .
For a twelve valve there once was only a few choices available and only one for power,the marine 370's. Now with the EDM's being popular many choices are available to you and at various stages of HP. The easiest way to explain the difference is to a owner on a budget is this,do you desire a turbo upgrade to handle the fuel the 370's or EDM's have so you can manage EGT's?. If your answer is no to the extra addition of cash to be spent for either a bigger exhaust housing for your HX35 or the aftermarket turbo to do the job correctly,then as a newbie stay away for a injector purchase right now. The 275's you ask about are a 24 valve injector and will not work with your properly valved truck. No matter what you decide with injectors remember,if you add fuel you will need to add air to manage EGT's or you will have more problems than you want later.
3-Clutch. .
The question you ask about the clutch living with what you want to start with is a resounding..... NO!!. I have never ran a #8 plate in my 98 5spd 12valver but I can attest to the damages incurred with the #10 plate and a good tune job. The stock clutch was toast within a very short amount of time. The first Centerforce I had came apart in less than 15,000 miles and the replacement was junk when EEP pulled it a few years ago for one of their double disc units. There were 2 twisted off input shafts in that ordeal and lots of labor money spent until I became a member here and realized what mistakes I had made. To accomplish what you want a clutch will be a order of business for your credit card early. BTW,A 8plate is designed for a automatic and not for a stick. I do know guys who use them, but,they have EGT issues without the addition of a good turbo.
Now for the common sense approach here for you as I had two people here who drilled this into me a while ago and I'll pass it on to you. 400/900 is a very attainable goal for your truck if you handle your purchases correctly. You will need to address other issues first before you step on the road to tuning and making your truck run like you want. Your first question to yourself should be this. . Do I want to do it the right way and have my truck last or do it the wrong way and create possible engine damages?. If you decide the right way is it then your very first purchase should be a set of gauges to monitor the engines boost and EGTs at the very least. You will never know what affects your changes made will have to it without them. A good air filter is next to allow her to breath fresh air for your heat control and quite possibly a step up to a 4" exhaust would be a good addition to remove the heat.
You next consideration is what fueling plate to buy and what mods should be done to your driveline as its the weakest link. If your going to a heavy fueling plate you will not only need a good turbo to manage EGT's you will need to upgrade the clutch and possibly the input shaft to keep from breaking them unload the higher torque loads. Lots of choices to be made here and lots of research for you to do on it before you jump into this group of BOMB's.
Do lots of research,ask alot of questions,do the work in small steps so you know what helped or hindered your choices and make wise use your money spent. You would be suprised on how much money gets spent in these halls on stuff that gets sold a short time later. I hope this helped and I wasn't to windy. I know I missed some things and short answered a few but with the vast search engine we have here you would be suprised what you will find to read. Good Luck on your quest... ... . Andy
Attention: TDR Forum Junkies 
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that will accomidate for the mods you have/will be making. my initial goal was 500/1000, my stock turbo is whats holding me back at the moment. my mods are listed in my profile, it sounds like thats where ya wanna be horsepower wise (currently 432/963. )
