Here's a few thoughts on the sequence of power mods:
Doing the larger TBI without boring out the intake to match will work, however you won't see as large a diff in performance, breathing thru the smaller intake holes.
This injector pod spacer is a cheap way to get more airflow out of your existing TBI:
https://www.independent4x.com/merch...p?cPath=64_65_75&products_id=293Being on a budget, the most Bang for your Buck$ at this point would be to upgrade the exhaust. These motors respond very well to airflow upgrades, but if you can't get it out of the engine, don't make a lot of diff what you're putting in.
Have a muffler shop chop off the old cat at the exhaust "wye" and splice in a new 2-1/4" exhaust system including upgraded cat.
Since you're trying to go economical, a generic "turbo" muffler and Catco brand (or otherwise cheap cat) replacement cat will do the job, and you'll have a nice growl at idle without irritating booming going down the road.
There's a lot of places online where you'll find inexpensive exhaust components, also take a look at
www.jegs.com or
www.summitracing.com to see what they offer.
Here's a Magnaflow performance 2.25" cat I found at one site for less than $55 shipped:
http://www.autopartswarehouse.com/sku/Ma...+%26+DrivetrainHere's an $18.95 shipped turbo muffler I found at Amazon with a simple Google search for "turbo muffler":
http://www.amazon.com/Thrush-17715-Muffler-Overall-outlet/dp/B00029J3AWPlenty more stuff like that out there, I'd guess.
If you have a decent local muffler shop (not a chain, they all Suck!), they may have competitive pricing on the parts. Have them bend up a new tail section without all the extreme bends of the stock exhaust. If you take a look underneath you'll see how the muffler can be angled better for a straigher flow, then you don't need all the crazy kinks the factory used.
Once your exhaust is finished and your finances allow, another good improvement is to add 1.6:1 roller-tipped rocker arms. The increased ratio from stock rockers will increase valve lift, just like installing a performance cam but a lot easier since you don't have to tear the front of the motor off, or even remove the intake.
Comp Cams makes a nice set of Magnum roller-tipped rockers for the GM V6, they are very nice and also a bit $pendy.
Small Block Chevys use the same type of rocker arm. The only difference is the V8 rocker arm balls mount on 3/8" studs whereas the V6 rocker balls mount on 10mm studs. So, if you pick up a set of V8 1.6:1 rockers and use V6 rocker balls, you're good to go!
I used a set of Magnum rockers in my old 2.8 Troop (which my folks now have), and the rockers are still working well after 12 years of family ownership. As are the cheap eBay V8 rockers I put in my 3.4.
http://www.compcams.com/information/Products/RockerArms/MagnumRoller.asphttp://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=390152589021&http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=200423477492&Either way they work great and really pep up the powerband, especially when combined with improved exhaust.
Once you have that taken care of, later on you may want to try the 4.3 TBI mods (but you'll still need to bore the intake for best effect).
With better exhaust you probably will notice a difference even without boring the intake, but it really does make that much difference to take out the holes the same size as the 4.3 TBI.
If you don't bore the intake and use the 4.3 TBI, you'll definitely have to use the spacer or the throttle plates will hit.
Take note that with a TBI spacer you can't flip the air cleaner lid. The lid will hit the hood (unless you have a body lift). That's why I cut a hole in my air cleaner and spliced in another air snorkel off an old S-10 air cleaner. I couldn't stand the noise of a "swiss-cheesed" air cleaner lid (which was my Poor-Man's breathing improvement for a while!). With a Non-Holey air cleaner lid in its normal position, the dual-snorkels flow plenty of air for even a 3.4.
The advantage of having a fully functional air cleaner with heat stove working is faster warmups in the winter. If you flip the lid you're not gonna suck in much warm air off the exhaust manifold.
Definitely gotta do something with the air cleaner though, unmodified it's very 'wheezy' and really holds the motor back. The Power Tips article had some good suggestions on that.
Re: boring the intake, if you're really handy you can bore it in place with a hole saw (I used a 90 deg drive attachment chucked up in a 3/8" electric drill). Just stuff lotsa rags down the intake to keep the metal chips out. Then vacuum out anything that did slip by.
It won't be as pretty as an intake done at the machine shop, but it'll work.
Note that you'll need to bolt that metal spacer onto the intake to keep the hole saw from walking around.
Anyway, there's a few thoughts for ya! I'll be sending along some swap info in a bit too. Enjoy!.......ed