What do you think will make more power stock S5 or stock S5 with a dellorto 48 DLHA ?

 

properly tuned fuel injection should be your best bet

 

Exhaust. Piggy back.

Those two have the most impact on power in an N/A for the money. Most everything else short of a full ported build is hit and miss.

 

The Racing Beat 48 DLHA kit was designed to produce about 177bhp on an 84-85 13B 4-port engine with full racing exhuast. The carb is out of production, and Racing Beat only sells a few parts from their original kit, so it's probably not the best choice right now.

That carb kit was outdated before this forum began, so there probably isn't a whole lot of info via Search.

 

S5 Tii