equate,
it'll help a little bit. You'll probably notice a little bit more power in mid-range and top end. You won't get quite as much power as you would if you were to convert to MAF. Also, converting to a Mass Air Sensor can be a bit expensive.
As an alternative, you could try do an M30 AFM conversion like the one that Dave did for his 92 MTech. I think he has a pretty good write up on his web site
www.davelength.net
You can make one by getting the parts from a local junk yard. I'd recommend keeping your old one intact and get a complete set from a junk yard to work with.
As for the Big Bore, BMP has one that is about 4.5mm larger (I believe). It runs $299.95 plus shipping and a $175 refundable core charge. If you want to do it yourself at a local machine shop, it'll run you more money (at least it would here in the Bay Area judging from the shops I've talked to).
Hope this helps.