The decreasing lead time of the quick-line plant makes it competitive at a lower inventory carrying cost.
( ( ( The ( decreasing ( lead time ) ) ) ( of ( the ( quick-line plant ) ) ) ) ( ( makes ( it ( ( competitive ( at ( a ( lower inventory ) ) ) ) ( carrying cost ) ) ) ) . ) )
(ROOT (S (NP (NP (DT The) (VBG decreasing) (JJ lead) (NN time)) (PP (IN of) (NP (DT the) (JJ quick-line) (NN plant)))) (VP (VBZ makes) (S (NP (PRP it)) (ADJP (JJ competitive) (PP (IN at) (NP (DT a) (JJR lower) (NN inventory)))) (S (VP (VBG carrying) (NP (NN cost)))))) (. .)))
It's not only the decreasing lead time of the quick-line plant that makes it competitive, it's also the small amount of inventory. 
( ( It ( ( 's ( not only ) ) ( ( ( the ( decreasing ( lead time ) ) ) ( of ( the ( quick-line plant ) ) ) ) ( that ( makes ( it competitive ) ) ) ) ) ) ( , ( it ( ( ( 's also ) ( ( the ( small amount ) ) ( of inventory ) ) ) . ) ) ) )
(ROOT (S (S (NP (PRP It)) (VP (VBZ 's) (ADVP (RB not) (RB only)) (NP (NP (DT the) (VBG decreasing) (JJ lead) (NN time)) (PP (IN of) (NP (DT the) (JJ quick-line) (NN plant))) (SBAR (WHNP (WDT that)) (S (VP (VBZ makes) (S (NP (PRP it)) (ADJP (JJ competitive))))))))) (, ,) (NP (PRP it)) (VP (VBZ 's) (ADVP (RB also)) (NP (NP (DT the) (JJ small) (NN amount)) (PP (IN of) (NP (NN inventory))))) (. .)))