LS1Tech has it set so that the attachments in posts are displayed as a thumbnail. However, with a few extra steps, you can display a normal sized attachment inside a post.
When you upload an image(s), you'll see the filenames of the uploaded image(s) as seen in this step:
Right-click on those filenames to get the URL/Address for each uploaded attachment. Copy the URL/Address for each uploaded attachment and place each of them inside a set of [img][/img] tag.
I've demonstrated, in this post, the above by uploading the LS1Tech banner as an attachment, and then copied/pasted the URL/Address of that uploaded attachment and placed it inside a set of [img][/img] tag.