As a resident of Heywood Road since 1982, please give due consideration to my comments as they are supported by my local knowledge and experience for the last 38 years.
I object to the proposed developments, for the following reasons:

TRAFFIC:

The route from Heywood Road to Diss Centre leads to Mount Street which is too narrow to accommodate 2-way traffic, so even now, traffic comes to a halt and has to wait for oncoming traffic to complete a 100 yards stretch of road, so it is effectively single file roadway. The proposed development would exacerbate this existing problem, if traffic increased on Heywood Road. At the same junction Heywood Road leads to Sunnyside which is also single file traffic for 200 yards. The 3rd road on the same junction is Walcot Road which is narrow and very busy during entrance and exit times to Diss High School.
Also the proposed link road from Shelfanger Road to Heywood Road would also increase traffic down Heywood Road and further exacerbate the problem outlined above. In summary any increase of traffic in Heywood Road going south in the direction of Diss centre, would make existing problems far worse, and gridlock situations would become even more commonplace. (On occasions, I have literally had to get out of my car to guide other motorists, until a road jam has been unlocked,).

As a constructive comment, I suggest that the GNLP0119 and GNLP0291 development might possibly be viable in purely traffic terms, if the access point for traffic from the development was in Shelfanger Road alone, as this road does not suffer from the same levels of congestion as the Heywood Road route into town. In this scenario GNLP0250 could be allocated to Cemetery expansion, which will be needed given the demographics of an ageing population.

POSSIBILITY OF NEGATIVE VISUAL IMPACT/BEING OUT OF CHARACTER WITH EXISTING PROPERTIES:

The existing properties in Heywood Road are all different in styles and ages. Any development facing Heywood Road would need to take this into account, and present a design and quality of housing that is compatible with the existing properties.

CONSIDERATION OF THE BIGGER PICTURE - HOW DISS WILL EXPAND:

Diss is in need of a bypass, which is supported by the fact that the A1066 as it passes through Diss has increasingly witnessed traffic coming to a standstill. Traffic destined for Thetford uses the A1066 through Diss, as there is no link road from the excellent A143 route to provide access to Thetford. Consideration should be given to where a bypass may be built, as if it uses the A143 route and a new link road to the A1066, there would be no point in further developing land to the North of Diss, and increasing the traffic going through Diss to get to the A143 and A1066.

HIGHWAY SAFETY:

A large volume of Diss High School children cross the road as they come in and out of Walcot Road.
This already is potentially dangerous for the children and causes a problem for the motorists travelling from all 4 directions of the staggered Walcot Road/Sunnyside junction. Again, any increase in the traffic using Heywood Road would increase the existing safety risks.