Using info gleaned from SMJ's info here: topic20836.html I went ahead and did the 100k/105k service today at 101k. Figured since I had to do the spark plugs, which were burnt down to nearly a pin head by the way, I might as well take the intake off and install my spacer I've had sitting around for 6 years. I think it took me like 5 hours to flush the coolant and replace it, XTP intake spacer, spark plugs, idler pulley, tensioner pulley, new serpentine belt, clean and recharge the air filter and toss the front skid plate. I took a lunch break in there and worked on some other car issues so it wasn't 5 straight hours for just this.
That spacer definitely changed the feel of the acceleration and the intake sound is more pronounced through the Nismo filter on a stick I have. Thanks to SMJ for posting details in that thread. Maybe now I'll get around to installing the NIB JBA headers I have sitting there in a milk crate.