change of carby might give you a bit better low end power, but bugger all up top. Some people will argue that Vitara carbs are better than Sierra carbs, but with 20 years and 160000km's on my Sierra, I've overhauled it once, and it starts first click of the key every time and runs like a dream. Personally, I'm not a fan of the Mikuni carbs and their plastic fuel bowls (similar to early Magna's). Question you gotta ask yourself is, is it worth the frigging around to install a Vitara carb for the benefits it may or may not provide

What additional trickery do you speak of Joe?

Had a go at this same thing last weekend. Joe is the man when it come to this but its not that hard really

Using the vitara inlet manifold makes it so much easier to do but is not necessary. From memory, the 1.3 manifold has an extra coolant output that has nowhere to go on the vit carby. I presume that you can just block this off but i had the vit manifold so i didnt need too.

You dont need any adapters to fit it, however you will need to modify a 4 wire plug from the vit carby to mate with the 3 wire sierra plug. Also you will need to adapt the sierra carby hat/airbox to fit the vit carby for ease of install. A 10mm high metal ring (like an egg ring) needs to be fitted between the carby and hat if you want to use the sierra one.

As for the air box flicky bit?? If this is the valve that directs hot air into the carby when cold and flicks over to cooler air when warm, i scrapped that ages ago but if you were to adapt the 1.3 carby hat to suit, i dont see why it wouldnt still work.

I had it on for the weekend and it felt to have a bit more low down power, allowing me to short shift a bit more. As for top end, i didnt feel that much but i don't know if i had i plumbed up properly and also they are well known for running rich so getting it tuned may improve this even more.

I had good fun learning most of this for myself so i hope it helps. Anyone with more knowledge on the matter feel free to correct me if i'm wrong