salam...
The bottom line is that the hadiths or personal views cannot contradict quran...
With regards to the traditions of some shia books that Nasibis shamelessly quotes, we should point out that these traditions have been deemed by the Ulema to be weak narrations. In addition to this Allah (swt) takes the responsibility of protection of the Qur’an Himself by declaring:
' Certainly We revealed the Reminder and certainly We shall preserve it." (The Holy Quran'
When Allah (swt) provides a guarantee that it is protected, any hadith of tahreef automatically has to be rejected. We do not deny that these traditions exist, but the Nasibis should know that there is a difference between tahreef traditions and basing one ;s aqeedah on those traditions. The ultimate standard to determine the authenticity of any hadith is the Quran, if it conflicts with Allah (swt) ;s Book it must be disregarded.
There are many saying of the Imams of Ahlul Bayt

that clearly vouch for the authenticity of the Quran, being the same unaltered text revealed to Prophet Muhammad (S) by Allah (swt). There are numerous traditions from the Imams that prove this point,so why one shall accept the points of tahreef in quran from any common scholars instead of the statementds of Imams and the Quran?
Commander of the Faithful Imam Ali
We did not make humans rulers, but we made the Qur’an the ruler over humans. This Quran is free from change but does not speak on its own accoard, an interpreter is needed for this task.Nahjul Balagha part 6 page 7, Publishers Rehmania Egypt
Hadhrath Imam Jafar Sadiq 
Ali bin Salam narrates from his father who asked Imam Jafer Sadiq

,O descendant of Prophet (S). What are your views on the Quran? Imam Jafer

replied and ;the Quran is Allah ;s book; it contains commands of Allah; sent by Allah. It is not subject to alteration, neither can anyone claim that it has been changed, nor has anyone ever made such a claim.
Amali-al-Shaykh Saduq, Page 545, Published Iran
Hadhrath Imam Ali Naqi 
The whole Ummah agrees on the authenticity of the Quran. No sect in the Ummah denies this fact, and this claim is true.
Ehtijaj-e-Tabrisi, Page 234, Published Iran)
Comments of Shia scholars refuting these lies
Shaykh Saduq (R.A)
The greatest Shia scholar of Hadith, Abu Jafar Muhammad Ibn Ali Ibn al-Husain Ibn Babwayh, known as "Shaykh Saduq" (309/919 - 381/991), wrote:
"Our belief is that the Quran which Allah revealed to His Prophet Muhammad is (the same as) the one between the two covers (daffatayn). And it is the one which is in the hands of the people, and is not greater in extent than that. The number of surahs as generally accepted is one hundred and fourteen ...And he who asserts that we say that it is greater in extent than that, is a liar."
1. Etikadat Shaykh Saduq 93, Published Iran)
2. Awail-el-Mukalat, Page 55-56, Published Najaf
3. Shi'ite Creed (al-I'tiqadat al-Imamiyyah), by Shaykh Saduq, English version, p77
Allamah Muhammad Ridha Mudhaffar
"We believe that the Holy Quran is revealed by Allah through the Holy Prophet of Islam dealing with every thing which is necessary for the guidance of mankind. It is an everlasting miracle of the Holy Prophet the like of which cannot be produced by human mind. It excels in its eloquence, clarity, truth and knowledge. This Divine Book has not been tampered with by any one. This Holy Book which we recite today is the same Holy Quran which was revealed to the Holy Prophet. Any one who claims it to be otherwise is an evil-doer, a mere sophist, or else he is sadly mistaken. All of those who have this line of thinking have gone astray as Allah in Quran said:
"Falsehood can not reach the Quran from any direction (41:42)"
The Beliefs of Shi'ite School, by Muhammad Ridha Mudhaffar, English version, p50-51
Allamah Muhammad Hussein Tabatabai
This renowned scholar of the Quran writes in his very famous exegesis, Tafseer-ul-Meezan, 12th edition, page 109, Published Iran:
The Quran, which Almighty Allah descended on Prophet Muhammad (S), is protected from any change.
Scholars of Ahlul Sunnah that have vouched for the Shia viewpoint
Despite the belated efforts of these Nasibis in spreading lies, there are true humble Sunni Ulema that have looked beyond these lies and have confirmed that the Shia believe that the Quran is the uncorrupted Word of Allah (swt).
Imam of Ahlul Sunnah Allamah Shaykh Ghazzali of Egypt
Whilst addressing the allegation that the Shia ascribe tahreef to the Quran. He said:
In one gathering I heard a man say that Shi’as have a different Quran, which is unlike the Quran we have. I asked him, and Where is that Quran? Islam is being practiced on three continents. Since the demise of the Holy Prophet (S) until today, a passing of fourteen hundred years, the Ummah has known of the existence of only the one Quran, we possess knowledge of where the chapters begin and end, end as well as the number of verses that they contain. Where is this other Quran? During this long passage of time how is it that any man or jinn have not located this and other Quran? These lies cause dissention between brothers and cause dissention about the Book. There is only one Quran, if it is published in Cairo, it is considered holy in Najaf and Tehran as well, they will hold it in their hands and keep it in their homes. They have nothing but respect for the Creator that sent it, and the person through whom it was revealed. Why then are such rumors and lies spread about people and this message?
Wafa an Al aqida wa Al Shariah, Page 265-266, Publishers Al kutub Al hadisia, Egypt, 1985
Principal of the Shariah Department of Al Azhar University, Allamah Shaykh Muhammed-al-Madani
To state that the Shia Imamia believe that the Quran on account of traditions that can be located in their texts, is just the same as reaching the conclusion on the basis of such references in our books and but both Shia and Sunni scholars have refuted these claims. None amongst the Imamia Shia and Zaidia believe in this lie, in the same way that none of the adherents of Ahlul Sunnah do. Whoever accuses the Shia of ascribing to tahreef of the Quran, should read books such as Allamah Suyutis Tafseer Itqan; and objectively look at the traditions that point to tahreef of the Quran. Although we do not accept these sorts of traditions, one Egyptian scholar in 1948 wrote a book titled Al Furqan, in which he copied many of these traditions from the works of Ahlul Sunnah. Should we on this basis conclude that the Ahlul Sunnah do not believe that the Quran is complete? Or should we on account of these traditions which were copied by someone or written in such and such book by such and such a person, adopt the viewpoint that the Ahlul Sunnah believe that the Quran is incomplete? The same conclusion could likewise be reached about the Shia, as like us they also have similar traditions in their books.
Risalahthul-Islam, 11th Edition, Pages 382-383, 4th Part
Imam of Ahlul Sunnah Shah Abdul Aziz Muhadith Dehalvi
Shah Abdul Aziz Muhadith Dehlavi an anti shia scholar , while acknowledging that the Shia do not believe that the Quran had been altered states:
It is proven from all the traditions of the Imamia that the Ahl’ul bayt used to recite this same Quran and based their decisions in accordance with it. The commentary of Quran by Imam Hasan Askari is the commentary of this (same) Quran. All his children, relatives and servants studied ‘this’ Quran, and he used to order them to recite this Quran when praying. It is due to this fact that Shaykh Ibn-e-Bawia in his book Al Aqidath, denied that Quran had been altered.
Tuhfa Ithna Asharia, Page 281, Published Istanbul
Edited by BOY-NICE, 08 July 2003 - 01:18 AM.