With the engine from the Golf Mk1 Tin Top came the Weber Alpha ITB's
Thanks to their design and manufacturing, the Webers 45mm ITB provides better throttle response and power delivery over stock throttle bodies. They flow more air and allow for more precise control of the air/fuel mixture. The Alpha Webers specifically are higher-performance throttle bodies that are commonly swapped into tuner/performance cars instead of stock throttle bodies. They help increase horsepower and torque when adequately tuned and matched with other supporting mods. Their benefits include better acceleration, a more linear power band, increased peak power, and greater tuning flexibility compared to stock inlet setups.
I used some Vauxhall Calibra Turbo 4x4 injectors from a 1992 model. The Calibra Turbo produced a healthy 201bhp and 207lb, so these injectors were up for the job and free.
Individual throttle kits are expensive. The base units are around £1000, and the additional parts needed to complete the setup soon add up. The inlet manifold, injector seats, ram pipes, and throttle body linkage will easily set you back £500, pushing the cost new to around £1500 for a 25bhp - 35bhp gain.
Luckily, I got my kit second-hand, £450 for the bodies and £500 for the additional parts.
Bike carb would have been a cheaper option, but the lack of the ability to map the fuel has its disadvantages, especially with a cam setup.
The throttle position sensor is a Magneti Marelli PF4B. These were used in the Ferrari F40 1992 and once were cheap but now cost lots second hand. I found a pair on eBay for 1K
I also found a new one in the States for $430
The Ford Sierra RS Cosworth 4x4 & Escort RS Cosworth used the PF09 throttle position sensor, which looks the same, but two wires need swapping to get it to work with the DTA setup. These are much cheaper at about £60, so it would be wise to swap them out at some point. But if it ain't broke.
