Thoughts from '01 Sport & '91 Navajo owner
I too have an '01 black Sport & have thought initially that parts were hard to find, but they lately have been becoming more prevalent. I also compare alot of my upgrades to my older, but very reliable '91 Navajo, on both a dollar & performance basis.
My opinion (may not be shared by all) is that as far as performance mods go, the '01 is a bit more difficult as the ECU seems a lot more picky about upgrades (ie. even my upgrade to Apten chip followed by free-flow exhaust led to check engine lite & horrible running, & YES, I did disconnect the battery over nite).
But, some parts just beg to be installed. I purchased the Gibson exhaust (I think truckperformanc.com has them) & am VERY happy with it...I pulled my 3200lb Maxima loaded w/1700lb of stuff across the country 2 wks ago & averaged 21mpg the entire way at 65mph cruise w/o any probs (& my oversized 17" performance tires actually throw off my speedo by about 4% so in reality I was a little closer to 22mpg). I have a Bullet custom 2.5" setup on my Navajo that gave similar results...a deeper, throatier sound that I find pleasant & noticeable (at least to me) improvement in mid-range acceleration.
K&N drop-in filter was a minor improvement but the KKM intake is on its way. I tried the KKM on my Navajo but it never seemed to run right so just go with the drop-in K&N on it at least. I anticipate the KKM will do better on the '01 (at least I hope)
Despite what alot of people say & all the hype, the Granatelli MAF upgrade was an awesome improvement on the '91...you WILL feel the difference at least on the older models. I have tried two on my '01 but continue to get check engine lites d/t presence of free-flow exhaust so had to have one programmed specifically for the KKM & free-flow exhaust (not back yet so can't tell you whether it works well yet or not)
I did a TB spacer on my '91 & once again I felt an improvement. Despite what is said, people have stated that upgrading to a larger bore TB will improve the performance, which sounds logical. But, the spacer is effectively enlarging the length of the TB, hence it TOO will increase the volume of the TB chamber & I would guess that is how it has helped with both mileage & performance. I am not an engineer nor automotive tech, these are just my own observations. Now, as for a TB spacer on the SOHC in our '01 Sports, I am not sure...it too is on order, but rather than make a bunch of mods at once, I am going to continue to methodically place them & ensure each one works before moving on.
All of those upgrades for performance are available & can be found by following threads both here & search engines.
I will tell you, though, that there IS performance to be extracted from your Sport, but it is pricey & does take some work, unlike it appears, is the case with the 5.0 models.
I did just put the screenfront onto my Sport (left it it's original black color) from Explorer Express & think it looks outstanding, so that is an option. Painting the lower body cladding, as a couple of people here have done is an awesome thought too, as well as the smoke tint for the taillites (Streetbeatcustoms.com).
If you don't have factory sunroof, installed electric ones that look fantastic & work great are pretty easy to find...I use mine all of the time & rarely have to turn on the A/C or open side windows (both of which dec MPG much more than having the sunroof cracked open a bit).
Hope my ramblings help a bit but if you have other questions, there are alot of very helpful people out there. Explorer Express is absolutely AWESOME & if you call them, chances are you'll talk directly with John & he'll answer any questions that you might have as well as give you advice/options.
As for my '91 Navajo (for example)...154K mi on stock engine & tranny...stock tow pkg with 4.11 (I believe) gear ratio (so quite low gear ratio for good off-line torque to pull) with aforementioned upgrades = consistent 17mpg in mixed driving, 23 mpg pulling 5x8 UHaul trailer twice from SoCal to Spokane & very good low-end & midrange power....what more can I say? Such is the reason for me at least to stick with this model, plus I think they look outstanding (even if they do ride rougher than the 4dr d/t shorter wheelbase).
Also, suspension is easy upgrade with Explorer Express....talk to John.
Sorry, way too long but I myself was in your shoes just about 6 mos ago...now I drive my Explorer alot more often than my 2000 Maxima.
Craig