i never have any of my cars steamed i think its bad for them tbh, im sure folk will argue this but its just something i wouldnt personally do, i can see why u would want to do this as it is hard work getting it clean by hand
all i used to get mine to how it is now are
Autoglym engine degreaser
Gunk Engine degreaser (spray and brush on)
WD40
Cilic bank either orange or purple bottle cant remb which
Various sandpapers and wet and dry papers
brilopads
dremel
dril with wire brush
high grade metal polish
lots of time and hurting fingers ehehe
im gonna grab the samco kit at some point
if you cant be arsed with changing bits a good clean of the engine will make it look 100 times better and presentable, wont be hard to do, u just need rags and the degreasers plus WD40 is essential
do all the suspension struts first, and fire wall etc then move onto the rocker cover etc
i also treat all my rubber bits inc hoses, slam panel etc with autoglym bumper care, but once applied i buff it off
If you do all this u will see a massive difference, just do it bit by bit in your spare tme
i wipe the bay down all the time, its not a bad bay for collecting water spray in the wet like my other car is but you still sometimes get some spray on the firewall (minimal tho), so i just monitor it and have a wipe down regardless every few days... very anal i know

so basically if i was u id do it by hand bit by bit using the degreasers i did, autoglym one is great for some bits and the gunk is better for others
remember tho WD$) is needed for gearbox etc or alloys that have been degreased, if not they will go all dry and then turn white
P.S Cilic bang is also great for some metal parts too, trust me
