Longganisa is pork, pork fat, sugar and garlic in a casing. The sweet Pampanga style (hamonado) is about 320 calories per 100g cooked, and a lot of that is sugar, 8 to 10g per sausage. The fat renders out in the pan and most tapsihan cooks tip it back over the rice. That is why longsilog beats tapsilog by 50 calories even though the sausages weigh less than the tapa.
The style of longganisa changes the plate a lot. Vigan longganisa is garlicky, sour and leaner, about 240 calories per 2 pieces. Lucban is similar at 260. The skinless sweet ones sold at supermarkets are small, about 110 each, so 2 pieces is only 220. The tapsihan default is the plump sweet kind at 145 each, and the plate assumes that.
A longsilog at a Manila tapsihan is 75 to 110 pesos and usually comes with a cup of sinangag that is more like 250g than 200g. If the plate looks generous, count 400 for the rice instead of 320. Add a cup of 3-in-1 coffee at 90 calories and breakfast is close to 900 before 8am.