Engine smoke mod?

[Flybywire]

Looking at this poster you can see the smoke from the engines...is this possile?

http://cgi.ebay.com/ws/eBayISAPI.dll?ViewItem&item=6575754217&indexURL=0&photoDisplayType=2#ebayphotohosting

[CCIP]

The smoke was visible, but... I don't think it's possible in the SHIII engine; and further, it's not as visible as the picture would have you believe.

U-boats had a pretty good masking system that mixed the exhaust with water. Under most circumstances, it wouldn't be very visible at all.