So I finally brought the buggy home, and as soon as the festive season subsides the deconstruction will start. So I've got some turbo charged aspirations and I was wondering which gearbox will deliver some good quarter mile times anda good sustainable top-end?

 A 1200/1300 box will give you off the line acceleration a 1500/1600 give better cruising speed and more top end a Gt box goves even better cruising speed.

A lot will depend on your rear tyre size as you can end ep with massive diameter on a 1600/gt box where it will not drive in top gear below 60mph as it is out of the engines power curve.

I have. 1600 irs box with225/70 x15 tyres and the 2l motor it is quick off the line and cruises at 60mph with 2800 rpm on it will get to 90 in 3rd gear oth around 6000 rpm

The other runs a1300 box 31/10.5 x15 tyres and a 1600 beetle motor and it is quick off the line but that fastest it has been is 81.2 mph and has not got the top end. Cruises happily in top gear over 30 mph.

There are many many variations and not one that fits all.

You may find you will need a box specially built for your application. Have a look at rancho boxes.
https://www.vwheritage.com/shop/beetle/transmission/performance-gearboxes-uprated-parts/

  thanks guys, I guess I will have to start with the engine and first determine how much power I've got to work with before building or installing a box which can cater to my needs. Did any type ones come out with a 5 speed gearbox?

Not as far as i'm aware, but places like Cogbox can build 5 speed boxes.

might be wrong, but have heard that the 5 speed beetle boxes have the same top ratio as the 4 speed, a Porsche can be used, but is pricey, the option I am looking at for the future is the upside down Audi/passat 5 and 6 speed boxes, another option is the converted Subaru bos,
Ttfn Glenn

As Mike said Cogbox will advise you and build you a gearbox, as will Bear in Birmingham

[My Youtube channel]

As Mike said Cogbox will advise you and build you a gearbox, as will Bear in Birmingham

Of course, shipping it out to you in Cape Town SA may be a little tricky!   

Ooff just spotted location.

I think the Subaru conversion looks a great option. You can slot an impreza motor straight in with the right ratios

Just for info, here's the link for Subaru gearbox conversion.
http://www.subarugears.com/index_files/Products.html
And sme info on the upside down Audi option
http://www.brick-yard.co.uk/forum/audi-a4-passat-gear-box-install_topic71714_page12.html
Happened across this while searching for other info, maybe of some use to you,
Ttfn Glenn

Ooh! So many options! Porsche, ScoobieDoo, upside down Audi/Passat, custom built gearbox from over the Seven Seas. I feel like a kid in a candy store, with nothing but holes in his pocket.
How about a Kombi gearbox? I'm sure on of you guys used that?

Porsche box is not a straight bolt in, modified subaru box will not be cheap, audi/ passat I have no idea but must be difficult to fit in a beetle pan cistom beetle boxes are £1000 over here but standard boxes are cheap and easily replaced so would suit your pocket a kombi gearbox may be unsuitable for the strip and road use as by design it is geared for shifting a heavy van.
a standard box will take the golf motor power I run 120bhp through a standard box both secondhand used units first one got changed after 15years bearing whine the second one was sold on after 14 years speedo now reads 190.000 miles and have gone  irs.
A contributing cause to failure is very wide grippy tyres so the load is placed on the diff rather than spinning the wheels but I do launch off the line but not with high engine revs.
You could always chop the gearbox horns off and make a frame to fot a complete alternative engine and box in from a FWD

Made a whoops and forgot the third link.
http://www.aircooledtechnology.com/index.php/transaxles
Ttfn Glenn

Made a whoops and forgot the third link.
http://www.aircooledtechnology.com/index.php/transaxles
Ttfn Glenn

Have not come across this stuff but you may need a mortgage for their engine/ trans kit at £6000 for an engine upgrade kit and you have to buy a complete built package to get a box.