another beams owner here! and i can vouch for everything everyone has said about this engine. i have had mine since about September and have loved every day of owning it. mine's a Beams motor straight out of a MR2 , unfortunately we were missing some vital wiring loom bits and pieces here  and there so ended up going with a stand alone ECU which solved all our problems. 
 
in regards to mods mine has ECU, Exhaust (custom made 2.75inch) and intake and is making around 127kw atw, its not much but its enough to keep me smiling like a goof when i put the foot down   
 
 

I suggest you have a drive of a beams mr2. You might find that its awesome and exactly what you're after. Or you might feel its not enough of an upgrade for the money and you start considering a turbo or v6 swap.

127 kw atw farrrk lol. I only got 110kw but I'm running a greytop with stock everything; actually gen 3 b-pipe and minor exhaust leak with sub-par intake jobby might have affected that dyno run so I'm gonna have another crack next dyno day.
If you're not in a rush, the best donor engine to find IMO is a redtop sourced from a Celica (SW20s as said are very rare and sellers will probably demand a premium...). Reason is because it has free-flowing extractors (supposedly worth 10hp over greytop) which alone is kinda hard to find if you already had a greytop like me.But as Adrian said it's best to try out one for yourself since experience>word of mouth (biased). If you're in Victoria there's a cruise coming up on the 23rd and I'm happy to give you a taste of ze Beams.
I still think the Beams is the cheapest option vs turbo (Gen 2 not worth considering) and V6 except maybe the 1MZ which can be had for cheaps but once again time/money spent on custom parts to fit

 
tree you still managed to give me a decent run when you were up in sydney though 
 
same offer applys rick if your in sydney id be happy to take you for a drive in mine to show you what beams life is all about 

Voodoo: 127kw at the wheels nice. I'd be interested in seeing how much mine makes never bothered putting mine on the dyno.

Rick: Like tree I'm based in Melbourne so if you are around I can give you a taste of a BEAMS powered car too. Furthermore if you do decide to go beams powered I can supply you a BEAMS SW20 body loom and dash loom :)

Ahh yeh when I saw "ECU, exhaust and intake" it all sounded too familiar in this small knit community heh. Your car was wayy faster than mine and it was like 2 car lengths by 80!! The next morning before I left Adrian's tho I found one of the spark plug ground electrodes had bent onto the centre electrode which explained the rough idle, but it's too far for a rematch haha
 

Thanks for the offers of a drive, but unfortunately i am in the far west of SA, so i don't know when i'd get to Melbourne or Sydney next. I went to both cities looking at MR2's to buy a month ago when i got mine lol.
I picked up a totally original 97 with only 125,000 kms on it.
 
I found a red top beams for sale here...
 
http://www.wholesalecarparts.com.au/all-parts/toyota-celica-20-3sge-beams-petrol-engine
 
any thoughts?

That one looks a bit rough to me. This one is much cleaner for the same price. It's also from a Celica:
 
http://www.ebay.com.au/itm/JDM-93-99-ST202-SS-III-Toyota-BEAMS-3SGE-Celica-Engine-Motor-Kit-Gearbox-3S-GE-/380836262672?pt=AU_Car_Parts_Accessories&hash=item58ab9c3310
 
If you have some money up your sleeve and want to save yourself the headache of tracking down the extra parts required to do the job properly using a Redtop from a Celica, you could just buy this one and import it:
 
http://www.ebay.com.au/itm/JDM-Toyota-98-Spec-MR2-SW20-3SGE-Beams-ABS-VVTi-M-T-Kouki-Engine-Motor-Clip-/321308090165?pt=Motors_Car_Truck_Parts_Accessories&hash=item4acf745f35
 
That will give you everything you need (including the stiffer engine mounts that came standard on the Japanese Gen3 Revision5 MR2 BEAMS models) and plenty of good spare parts for other things too. Nevertheless, even with an original MR2 BEAMS half-cut, you'll still need to get a good auto electrician to swap a few pins around on your Bathurst body loom.
 
No matter what anyone tells you, you should also know that the only way to get a BEAMS idling like a pussy cat and working at full power is to use the original MR2 BEAMS airbox and intake system. They're very hard to find too, which is another reason why spending more up front and buying an MR2 BEAMS half cut can save a lot of headaches later on.
 
Everything you need to know about what it takes to swap a Redtop into an MR2 can be found at this forum:
http://www.mr2.com/forums/forumdisplay.php?f=127
 
 

mister2: I couldn't agree with you more. Personally you are better off getting a BEAMS from an SW20 with the stock air box, however SARD makes a intake kit for the red top BEAMS that works very well if you are willing to pay over $400 including shipping, I have a stock air box system as a 'just in case' but I have been running the SARD one for a good 18 months.

Hey Darren. Good to hear the Sard intake does the job OK. I'd read varying reports on that.
 
One thing is beyond question for me, and that's that the BEAMS RedTop is an awesome engine. I've never had any regrets about fitting mine. I love it!